Compositions for controlling phytoplankton contamination

ABSTRACT

A composition for mitigating, inhibiting, ameliorating and/or eliminating phytoplankton growth in a waterbody, the composition comprising an active ingredient at concentration of 80.0-99.5% (w/w) of the composition and a coating material at concentration of 0.5-20% (w/w) of the composition; wherein the critical surface tension of the composition is between 15-60 dyn/cm and wherein the relative density of the composition, prior to being submerged in water, is above 1 g/cm 3 .

RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/IL2020/050115, filed Jan. 30, 2020, which claims priority toIsraeli Application No. 264657, filed Feb. 5, 2019, the entiredisclosures of which are hereby incorporated herein by reference.

FIELD OF DISCLOSURE

The present invention discloses compositions for cost-effectivemitigation of aquatic phytoplankton blooms.

BACKGROUND OF THE INVENTION

Under favorable conditions, yet not fully defined, the growth rate of adominant phytoplankton specie increases, leading to a large rise in itsbiomass, a process often term “bloom”. Intensification of toxicphytoplankton blooms, that may cover large areas, is a matter of growingconcern to the public, water authorities and environmental scientistsworldwide. Formation of various toxins by these organisms constitutes aserious threat to the water quality in lakes and reservoirs and theiruse for drinking water, recreational activities and irrigation. Clearly,the approaches currently used to limit toxic blooms, such as managementof the drainage basin (to reduce nutrient inputs), are expensive andunsuccessful.

Approximately 300 phytoplankton species—cyanobacteria (often calledblue-green algae) such as Microcystis sp. and microalgae are known toform massive blooms, many of them producing an array of toxic chemicals.Due to massive O₂ consumption in respiration, the blooms may causedepletion of O₂ and massive death of fish and fauna, and clogging of thewater pumps and filters. The annual global losses associated with theseblooms is estimated at many billions of USD (US EPA, Compilation of costdata associated with the impacts and control of nutrient pollution,2015).

Cyanobacteria are photosynthetic (gram-negative) bacteria. Manycyanobacterial species produce and thereafter release toxins (a.k.a.“cyanotoxins”) into the water either towards the end of the bloom orunder physical duress (e.g., during filtration or pumping) (Huisman, etal., Nature Rev Microbiol 16: 471-483, 2018). Studies showed thatcyanotoxins cause death and various illnesses in humans and animals whodrink, swim or even consume food that was exposed to infested water. Thecyanotoxins are not sensitive to boiling, and can only be treated toallow for drinking with heavy chlorination. The WHO recommendsprohibiting consumption of, or recreation in, water where toxiccyanobacterial biomass exceeds 10 μg/l chlorophyll-a (WHO, Guidelinesfor Drinking-Water Quality, Addendum to Volume 2, Health Criteria andOther Supporting Information, 1998) and may reach levels as high as 1100μg/l chlorophyll-a (Bertone et al. Environ Microbiol 9: 1415-1422, 2018;Otten et al. Environmental Science and Technology 46: 3480-3488, 2012;Huisman (ibid.)). Further, cyanobacterial blooms excrete massive amountsof polysaccharides into the water, turning it viscous. This phenomenonis sometimes also related to “swimmers' itch”—due to the itch causedwhen coming in contact with contaminated water. It further createsoperational problems for water utility companies that face regularlyclogged pipes as well as for farmers preventing them from usingdrip-irrigation systems.

Microalgae are a diverse group of eukaryotic photosyntheticmicroorganisms that includes several groups including green-algae, redalgae, brown algae, diatoms and dinoflagellates. They are responsiblefor clogged pipes in reservoirs used for irrigation or sewage ponds.Some algal species (e.g., Prymnesium sp., Karenia sp., Alexandrium sp.and others) are toxic as well and are responsible for massfish-mortality in aquaculture and marine environments. Illnesses andeven deaths are occasionally reported among people and animals thatconsumed toxic water or seafood contaminated with algal toxins.

Most phytoplankton blooms are treated worldwide with copper salts suchas copper sulfate pentahydrate (CuSO4.5H2O, CAS NO. 7758-99-8,“copper”), a relatively safe and effective algaecide that causes algallysis. However, in water with high organic load, mineral content or pHlevels above pH 7.0, its efficacy is reduced dramatically.

Other, less-frequently used algaecides are based on hydrogen peroxide(H₂O₂) either via direct application or its release from variouscompounds such as percarbonates. Cyanobacteria are far more sensitive toH₂O₂ than most microalgae (Drabkova et al. Environ Sci Technol 41:309-314, 2007). Thus, H₂O₂ treatments damage toxic cyanobacteria whilefar less affecting other algae.

As fish and some other water living organisms are sensitive to H₂O₂, itis required by the US EPA to avoid a full-lake application over thecourse of one day to allow those organisms to flee to untreated areas.

The mode of action of H₂O₂ involves the triggering of oxidative stress.Thereby it may prompt an autocatalytic cell-death cascade (Berman-Franket al., Environ Microbiol 9: 1415-1422, 2007; Spungin et al.,Biogeosciences 15: 3893-39082018) among the cyanobacterial population.

There is a vast, age dependent, difference in the ability of thecyanobacterium Microcystis sp. to degrade H₂O₂, as its decomposition byolder cells is much faster than in younger cells (Daniel et al,Environmental Microbiology Reports 11: 621-629, 2019). Toxic strains areless able to degrade H₂O₂ than non-toxic strains (Schuurmans, HarmfulAlgae 78: 47-55, 2018).

Currently used protocols of Microcystis sp. blooms treatments by H₂O₂rests on a single treatment of H₂O₂ as high as of 0.7-1 mM (Zhou,Chemosphere 211: 1098-1108 2018; Matthijas et al Water Research 46:1460-1472, 2012). All algaecide applications currently in use sufferfrom 3 debilitating shortcomings: (i) dose; (ii) timing of applicationand (iii) cost of application.

Current treatment protocols of algal blooms using various granularalgaecides is inefficient due to the immediate sinking of the particlesto the sediments. Thus, the exposure time of the phytoplankton to theactive ingredient (AI) is rather short. Consequently, very highconcentrations are used with serious environmental implications.

Even when dissolved copper solution or hydrogen-peroxide (in a liquidform) are applied, specialized equipment that is mounted on boats isrequired. For instance, Lake Delftse hout (NL) with ˜200,000 m² and avolume of 705,000 m³, was infested with toxic Anabaena sp. and wastreated with 5 ppm of 50% liquid H₂O₂, which totaled 3.5 tons and took 5hours to apply (Tsiarta et al., 2017). In another attempt to treat toxicAlexandrium bloom in Ouwerkerkse Kreek (NL), a 420,000 m³ water body,the treatment took two days, during which 21 tons of 50% liquid H₂O₂were applied. Total direct costs of this endeavor were €370,000 (Bursonet al., Harmful Algae 31: 125-135, 2014). Moreover, special measureswere taken in order to store concentrated H₂O₂ (delivery on the day ofthe application by a certified transport company; storage in arestricted area with an entrance on permission only). These types ofapplications are always carried out by professionals experienced inhandling chemicals. The complexity and price-tag linked to thesetreatments have reduced treatment-candidates almost exclusively to waterreservoirs that are smaller than 100,000 m² (Lurling et al., Aquat Ecol1-21, 2015) and even then—requiring long lead time to treatment,including mobilization and de-mobilization of said equipment, compoundand personnel.

The time of treatment is a critical element to its success. Recentlydeveloped remote sensing technologies (Kudela, et al., Remote SensEnviron 167: 196-205, 2015), coupled with onsite measurements, enablethe recognition of cyanobacterial population at an early stage wellbefore the development of massive blooms (Bertone (ibid.); Hmimina etal., Water Res 148: 504-514, 2019). Due to the presence of phycobilins(with specific absorption spectra) and absence of chlorophyll b incyanobacteria, it is possible to identify cyanobacterial presence(Bertone (ibid.); Hmimina (ibid.).

The currently employed treatments of toxic phytoplankton blooms lyse thecells and thereby release massive amounts of toxins into the water body.As intensification of aquatic phytoplankton blooms are a seriousecological problem worldwide, there is a need for novel methodologies toprevent the bloom development rather than await its full dimensions. Thepreventive treatment proposed here significantly reduces the amount ofaccumulated toxins and the concentrations of active agent needed, andthus the cost and environmental hazard associated with the treatment.

RELATED ART

Various chemicals are used to mitigate/diminish/kill/inhibitcyanobacteria blooms in water bodies by applying oxidative stress. Thisis accomplished either directly by singlet oxygen generation, or morecommonly by H₂O₂ or via reagents that release H₂O₂ such as sodiumpercarbonate or salts of various metals such as copper that inducesoxidative stress (Gu et al., 2019). Use of H₂O₂ to treat the bloomsrests on the fact that cyanobacteria are relatively sensitive to H₂O₂,as compared to other phytoplankton species (Tichy and Vermaas, 1999)(Matthijs et al., 2012) (Weenink et al., 2015) (Lin et al., 2018)(Daniel et al., 2019). However, the minimal H₂O₂ concentrations neededto kill the cyanobacterial cells seriously affect the populations ofvarious fish, zooplankton and phytoplankton species (other thancyanobacteria). Further, when the H₂O₂ was applied to treat acyanobacteria bloom in a natural water body, the cyanobacteriapopulation started to recover in 6-7 weeks (Matthijs et al., 2012). Forthat reason, in many parts of the world it is not allowed to treat waterbodies with H₂O₂ or other active ingredients that induce oxidativestress in cyanobacteria.

Several papers have shown that high concentrations of active agentresult in transient elimination of microalgae only.

-   -   i. Matthijs and colleagues (2012) (Matthijs et al., 2012)        examined the effect of H₂O₂ applications in Lake Koetshuis, The        Netherlands, and Plexiglas enclosures filled with water        therefrom. The lake was infested with the cyanobacterium        Planktothrix agardhii, a known producer of the toxin        microcystins, at concentrations as high as 2-8*10⁵ cells/mL in        the lake, and 2*10⁶ cells/mL in the Plexiglas containers. The        latter was 110 cm in diameter and 150 cm in height (but only 120        cm plunged in water). Thus, the surface area of the container        was about 9500 cm² and the water volume 1140 L. The lowest H₂O₂        concentration that sufficed to significantly reduce the P.        agardhii population was 2.5 mg/L, equivalent to 2.85 gr/m².        Already at this H₂O₂ concentration, the photosynthetic        performance and cell counts of zooplankton population were        severely reduced.    -   ii. The surface area of Lake Koetshuis is about 0.12 km².        Matthijs and colleagues (2012) (Matthijs et al., 2012) estimated        that the total lake volume was about 240,000 m³. As for the H₂O₂        concentration, they used 240 kg H₂O₂ for the entire lake,        equivalent to 2 gr/m². In lake experiments, the various        phytoplankton groups (green algae diatoms, cryptophytes and        cyanobacteria) were seriously affected by the treatment and the        level of the toxic cyanobacteria was rapidly rising already        after 6-7 weeks.    -   iii. On the basis of their laboratory and field studies, Weenink        and colleagues (Weenink et al., 2015) discussed “How much HP        (H₂O₂) has to be added for selective suppression of        cyanobacteria and at which density of the phytoplankton?” They        recommend using a minimum of 2.3 mg·L⁻¹ H₂O₂ per treatment and        that the higher the phytoplankton biomass, the more H₂O₂ should        be applied.    -   iv. In a mesocosm experiment, Lin and colleagues (Lin et        al., 2018) examined the effect of a range of H₂O₂ concentrations        (2-12 mg/L) on the population of Microcystis, several groups of        phytoplankton and of bacterioplankton assemblages. 150 L water        samples were withdrawn from Dianchi lake, China and placed in        plastic containers. The diameter of the containers was 56 cm        (not mentioned in the paper but kindly provided by author Prof.        Nanqin Gan). Thus, the container's surface area was 2,462 cm²        and the amounts of H₂O₂ added was equivalent to 1.22-7.31 gr/m².        Lin et al (2018) indicated that “The abundance of Microcystis        decreased when H₂O₂ was applied at doses of 4 mg/L (2.44 gr/m².)        and above. The cell density of Microcystis did not decrease when        the H₂O₂ dose applied was 2 mg/L (ANOVA, P >0.05). At 4 mg/L        there was a large decline in the population of various other        phytoplankton and bacteria.

All of the above studies suffer from one or more of the followingdrawbacks: inefficient treatment (the cyanobacteria population is noteliminated), transient effect only (the cyanobacteria population israpidly reestablished) or the dose is too high (above the highestallowed limit for drinking water and/or negatively affecting beneficialfauna in the ecosystem).

There thus remains a need for methods and compositions allowingefficient treatment of cyanobacteria, i.e. treatments allowing asignificant and lasting reduction in cyanobacteria efficiency, whilebeing ecologically sustainable, i.e. having minimal effect on otherphytoplankton and bacteria and using low doses of active ingredient(“AI”).

SUMMARY

The herein disclosed invention enables efficient treatment ofcyanobacteria, which reduces the cyanobacteria concentration for aprolonged period of time, essentially without negatively affecting otherphytoplankton and bacterial populations, which are important to theecosystem of the waterbody, while using low doses of AI, thus causing aminimal health hazard when consumed.

The effect is inter alia obtained due to the gradual andcontinuous/prolonged release of sublethal concentrations of the activeingredient programming the toxic cyanobacteria to cell death whilehaving minimal effect on other beneficial algal species.

The herein disclosed composition and method advantageously allowsapplying as little as 0.33 kg Sodium percarbonate (or other AI) per1,000 m² which is equivalent to 0.11 gr/m² (i.e. at least 11-fold lessthan the minimal effective amounts used in the abovementioned studies).

According to some aspects, the present disclosure is directed tocompositions for mitigating phytoplankton growth in water bodies, thecomposition comprising:

-   -   i. an active ingredient (also referred to herein as “AI”) at a        concentration of 80.0-99.5% (w/w)    -   ii. a coating material at a concentration of 0.5-20% (w/w)        wherein the critical surface tension of said hydrophobic        composition is between 15-60 dyn/cm and wherein the relative        density of the composition, prior to being submerged in water,        is higher than 1.0 g/cm³.

According to some aspects, the present disclosure is directed tocompositions for mitigating phytoplankton growth in water bodies, thecomposition consisting essentially of:

-   -   i. an active ingredient (also referred to herein as “AI”) at a        concentration of 80.0-99.5% (w/w)    -   ii. a coating material at a concentration of 0.5-20% (w/w)        wherein the critical surface tension of said composition is        between 15-60 dyn/cm and wherein the relative density of the        composition, prior to being submerged in water, is higher than        1.0 g/cm³.        According to some embodiments, the composition is formulated        such that the effective specific gravity declines below 1 g/cm³        in 0.01-120 minutes after being submerged in water leading to        surfacing of the composition to the water surface (FIG. 1).

The inventor of the present application unexpectedly found thatcompositions comprising an AI properly encapsulated with a hydrophobiccoating may, despite having a specific gravity higher than that of water(>1.0 g/cm³), float or at least resurface within 0.01-120 min afterhaving been submerged in water and remain floating even after mixing.This is further exemplified in the examples section.

The inventor of the present application unexpectedly found that wherethe specific gravity of a given hydrophobic coating material is lessthan 1.0 g/ml and that of the AI used larger than 1.0 g/ml, raising theproportion of the coating material in the encapsulated compositionslowed or even eliminated the floating of the AI material. As an example(see FIG. 1), a composition of 95% (w/w) of copper based-AI granules and5% (w/w) coating material floated slower (had a longer resurfacing-time)than a composition made of 99% (w/w) of the same AI and 1% (w/w) coatingmaterial (FIG. 1). Further, a 75% (w/w) copper-based AI with 25% (w/w)coating material failed to float and sunk to the bottom of the waterreservoir. This is further exemplified in the examples section.

According to some embodiments, the floating composition advantageouslyprovides a very high percentage of AI within the final product,requiring minimal product (i.e. algaecide) input in order to achieve anoptimal lethal concentration in the water. As a result, the hereindisclosed composition reduces the needed AI dose for treatment, theoverall operational costs and the time-to-treatment and thus provides asuperior sustainable course of treatment with minimal environmentalfootprint.

It was further found that a range of 15-60 dyn/cm surface tension of thecoating material is critical for acquiring buoyancy and that the lesscoating (w/w) applied, the faster the resurfacing took place and alarger fraction of the AI was found in the surface (FIG. 1).

Advantageously, the acquired buoyancy repeated itself when various AIcompounds were encapsulated, such as, but not limited to, calciumhypochlorite, sodium percarbonate, copper sulfate pentahydrate, aluminumsulfate and potassium permanganate.

Moreover, different coating materials provided similar beneficial andunexpected results as long as the critical surface tension of thecoating material was within the range of 15-60 dyn/cm.

Without wishing to be bound by any theory, a buoyancy of a singlenon-wetting powder on the water surface is defined by the interaction ofdifferent forces: buoyancy, curvature force, and gravitation. In thecase of sphere-like particles, it can be expressed as Mg/2σL sin(Θ)<1.0,where “M” is the mass of a particle, “g” is an acceleration of gravity,“L” is a contact length, a is a surface tension of water, Θ is atangency angle of the floating body, and 1.0 is the relative density ofwater measured in g/cm³. Hydrophobicity may play a major role byaltering the water-particle interactions and thus the angle of thefloating body. When large hydrophobic particles of 5-1,500 μm are placedon the water surface they may aggregate (possibly due to stronghydrophobic attractions) and form a meniscus at the water surface. Whenthe water-tension breaks (depending on various parameters such as, butnot exclusively, the water purity, temperature and others), thecomposition may descend to the bottom but resurface thereafter.

Without wishing to be bound by any theory, the surprising resurfacing ofthe composition having a specific gravity higher than 1.0 g/ml, may bedue to the hydrophobic characteristics of the composition.

As a further advantage, the herein disclosed formulation may beformulated to have a buoyancy enabling the composition to stay submergedbelow the surface of the water system yet without sinking to the bottom(also referred to herein as a partial buoyancy), e.g. to remain at adepth of 0 m-1.5 m, preferably between 0.2-1.0 m below the surface ofthe water system when applied. This may be particularly advantageous forpre-bloom treatment as the majority of the algal/cyanobacterialpopulation are found below the surface as compared to the floating matscharacterizing algal bloom (Bertone (ibid.); Kudela (ibid.).

According to some embodiments, the semi-buoyant compositions can beformulated for slow or extended release of the AI. As demonstratedherein, it was advantageously found that extended exposure of thephytoplankton to the algaecide, caused cell death even when the highestconcentration of the algaecide in the water body is below its knownlethal concentrations. It was further found that the sublethalconcentration of the AI alone killed the cyanobacteria while havingminimal impact on green algae and even allowed the recovery of greenalgae and enabled them to outcompete remaining toxic phytoplankton (seeFIG. 18 below).

According to some aspects, the present disclosure is also directed tomethods for controlling phytoplankton growth in water bodies by treatingthem preventively, i.e. prior to the appearance of dense populationoften termed “bloom” and/or prior to formation of algal mats on thesurface of a water body.

Advantageously, the herein disclosed treatment, conducted prior to thedevelopment of algal or cyanobacterial blooms, minimizes the amount oftoxins released to the water body by lysing cells. As an example, atreatment of a Microcystis sp. population as proposed here may releaseup to 0.01 μg/L microcystin-LR to the water body, i.e. 100-fold lowerthan the maximal allowance by the WHO(https://www.who.int/water_sanitation_health/water-quality/guidelines/chemicals/microcystin/en/).This is in sharp contrast to conventional treatments applied when theblooms are already established, where microcystin-LR level can exceed 45μg/L (Sakai, Scientific World Journal DOI:10.1155/2013/838176, 2013).

According to some embodiments, the method may include sedimentation ofgranules within the photic zone of the water body (the layer of water ina water body that is exposed to at least 1% of the light intensity atthe surface) that varies by season, geology, geography and thephytoplankton population density. According to some embodiments, themethod comprises administering a semi-buoyant composition formulated toremain within 0.02-1.0 m from the water surface. This is particularlyadvantageous for pre-bloom treatments during which a large proportion ofthe algal/cyanobacterial population are typically found 0.05-1.0 m belowthe surface (Bertone (ibid.); Kudela (ibid.).

According to some embodiments, there is provided a composition formitigating, inhibiting, and/or eliminating phytoplankton growth in awaterbody, the composition comprising or consisting essentially of anactive ingredient at concentrations of 80.0-99.5% (w/w) of thecomposition and a coating material at concentration of 0.5-20% (w/w) ofthe composition; wherein the critical surface tension of saidcomposition is between 15-60 dyn/cm and wherein the relative density ofthe composition, prior to being submerged in water, is above 1.0 g/cm³and wherein the relative density of the composition decreases below 1g/cm³ 0.5-60 minutes after being submerged in water.

According to some embodiments, the composition comprises or consistsessentially of an active ingredient at concentrations of 90.0-99.5%(w/w) of the composition and a coating material at concentration of0.5-10% (w/w) of the composition.

According to some embodiments, the composition may include granuleshaving a first concentration of coating material and granules having asecond concentration of coating material. This may advantageously ensurea prolonged duration of release of the active ingredient in that theactive ingredient is initially released from granules having a lowerconcentration of coating material and subsequently from granules havinga higher concentration of coating material.

As anonlimited example, the composition may include granules having 1%w/w coating material (and 99% w/w active ingredient) and includegranules having 3% w/w coating material (and 97% w/w active ingredient),thereby extending the release of the active ingredient over time.

According to some embodiments, the composition may be devoid of anencapsulated floating agent.

According to some embodiments, the coating material comprises a Behenicacid Octadecanoic acid, 2,3-dihydroxypropyl ester; Glyceryl distearate;Hexadecanoic acid; Octadecanoic acid; Fatty acids; Fatty acids, C8-18and C18-unsatd.; Fatty acids, C16-18 and C18-unsatd.; Fatty acids, C8-18and C18-unsatd., potassium salts; Fatty acids, C8-18 and C18-unsatd.,sodium salts; Glycerides, C8-18 and C18-unsatd. mono- and di-;Glycerides, C14-18 mono- and di-; Fatty acids, coco, polymers withglycerol and phthalic anhydride, a wax, paraffin, rosin, siliconederivative or a derivative thereof or any combination thereof.

According to some embodiments, the composition may have a meltingtemperature of 50-90° C. According to some embodiments, the compositionmay have a solidifying temperature below 20° C.

According to some embodiments, the coating material has an acid value of3-8 mg KOH per gram. This may advantageously provide an optimum adhesionbetween the shell (coating material) and the core (active ingredient).

According to some embodiments, the coating material comprises a wax,paraffin, a fatty acid or any combination thereof.

According to some embodiments, the concentration of the activeingredient is about 80-99.5%. According to some embodiments, theconcentration of the active ingredient is about 95-99.5%.

According to some embodiments, the concentration of the coating materialcontent is in the range of about 0.5-20%. According to some embodiments,the concentration of the coating material content is in the range ofabout 0.5-5%. According to some embodiments, the concentration of thecoating material is less than 20% (w/w) of the composition. According tosome embodiments, the concentration of the coating material is less than15% (w/w) of the composition. According to some embodiments, theconcentration of the coating material is less than 10% (w/w) of thecomposition. According to some embodiments, the concentration of thecoating material is less than 5% (w/w) of the composition.

According to some embodiments, the composition comprises granules havingdifferent concentrations of coating material. For example, according tosome embodiments, the composition comprises a first portion of granulescomprising 0.5-2% w/w coating material mixed with a second portion ofgranules having 3-10% coating material. According to some embodiments,the composition further comprises granules having a 6.5%-20% w/w coatingmaterial. The different concentrations of coating material mayadvantageously allow prolonged release of the algaecide when submergedin a waterbody and thus bring about prolonged exposure of thecyanobacteria to the algaecide (e.g. H₂O₂). Without being bound by anytheory, the prolonged exposure causes death, primarily programmed celldeath, of the cyanobacteria (rather than necrotic cell death),advantageously following a single treatment with the composition despiteusing small doses of algaecide. This is unlike the necrotic deathcommonly used where a much larger (at least 10-fold) concentration of AIis required.

According to some embodiments, when the encapsulated AI used is H₂O₂ theconcentration applied may be in the range of 10⁻⁷-10⁻¹² ppm depending onthe density of the phytoplankton population and the depth of the waterbody. It is understood that such concentration is significantly lowerthan that typically used in non-encapsulated compositions, namely2-4*10⁻⁶ ppm (see for example Matthijs et al., 2012: Weenink et al.,2015; Lin et al., 2018).

According to some embodiments, the critical surface tension of thecomposition is in the range of 20-45 dyn/cm or 30-45 dyn/cm.

According to some embodiments, the active agent comprises anoxygen-releasing agent, a chlorine releasing agent, a bromine-releasingagent, an iodine-releasing agent, a peroxide-based compound, a copperreleasing agent, a manganese-releasing agent, an aluminum releasingagent, or any combination thereof.

According to some embodiments, the composition may be formulated suchthat the active ingredient is released into the water system at watertemperatures below 45° C. within 24 hours of being applied.

According to some embodiments, the composition may be formulated asgranules with a granule size in the range of 10-1,500 μm or in a rangeof 300-1,500 μm or in a range of 1-10 mm.

According to some embodiments, the composition is configured to staysubmerged at a depth of about 0.02-1 m below the surface of the watersystem after having been applied and/or after or duringresurfacing/refloating (see examples below).

According to some embodiments, there is provided a method for preventingand/or inhibiting development of a toxic phytoplankton bloom in a waterbody, the method comprising identifying areas within the water body atoxic phytoplankton biomass above 8,000 cells/mL or a chlorophyll-aconcentration above 3 μg/L and applying a buoyant algaecide compositionto the area of the water body, such that the concentration of thealgaecide within the area is below a lowest lethal dose.

According to some embodiments, the applying may efficiently prevent analgal or cyanobacterial bloom when applied prior to the development ofthe bloom. According to some embodiments, the method may essentiallyeliminate algal or cyanobacterial infections when applied followingappearance of algal or cyanobacterial scum.

According to some embodiments, the applying is done when thechlorophyll-a concentration measured elsewhere in the water body isabove 3 μg/L. According to some embodiments, the applying is done whenthe chlorophyll-a concentration measured elsewhere in the water body isabove 3 μg/L and below 10 μg/L.

According to some embodiments, the water body comprises a reservoir, anocean, a lake, a dam, a pond, an estuary, a gulf, a sea, or a river.

According to some embodiments, the method further comprises applying asecond dose of the buoyant algaecide composition to the area 0.5-10hours after the first applying thereof.

According to some embodiments, the algaecide composition is configuredto release the algaecide for at least 2 hours after application thereof.

According to some embodiments, the composition is formulated to staysubmerged at a depth of about 0.02-1 m below the surface of the waterbody.

According to some embodiments, the water body is a water body withearlier events of toxic phytoplankton blooms. It is thus understood toone of ordinary skill in the art that while the composition and methodof applying same is suitable for use in water bodies with a first event,it was surprisingly found that even water bodies suffering from numerousevents of toxic phytoplankton bloom may be successfully treated usingthe herein disclosed method and/or composition.

According to some embodiments, the composition applied comprises80.0-99.5% (w/w) active ingredient and 0.5-20% (w/w) coating material,as essentially disclosed herein.

According to some embodiments, the composition applied comprisesgranules having different concentrations of coating material. Forexample, according to some embodiments, the composition comprises afirst portion of granules comprising 0.5-2% w/w coating material and asecond portion of granules having 3-10% coating material. According tosome embodiments, the composition further comprises granules having a10%-20% w/w coating material. This may advantageously allow prolongedrelease of the algaecide and thus a prolonged exposure of thecyanobacteria to the low algaecide (e.g. H₂O₂) concentration.

According to some embodiments, the coating material has a melting pointabove 45° C., above 50° C., or above 55° C. Each possibility is aseparate embodiment.

According to some embodiments, the coating material has a solidifyingpoint below 20° C., below 30° C., or below 40° C. Each possibility is aseparate embodiment.

According to some embodiments, the critical surface tension of saidcomposition is between 15-60 dyn/cm and wherein the relative density ofthe composition, prior to being submerged in water, is above 1.0 g/cm³.

According to some embodiments, the size of the granules is within arange of 0.3-15 mm, 0.3-1 mm or 1-10 mm. Each possibility is a separateembodiment.

According to some embodiments, the composition/the granules have aviscosity of 6-8 cP at 70° C.

According to some embodiments, there is provided a method for treating,inhibiting, and/or eliminating phytoplankton growth in water bodies, themethod comprising:

-   -   i. performing inspection for presence and density of a        phytoplankton (e.g. according to specific phytoplankton's        pigments),    -   ii. defining an infected area by coordinates,    -   iii. applying a buoyant composition locally, up wind—while        having the wind in the back, opposite to the infected area, so        that the wind pushes the floating algaecide composition        particles towards and/or with the infected area, thereby        treating, inhibiting and/or eliminating the development of        phytoplankton bloom.

According to some embodiments, the treatment may be preventive, thusenabling treatment with a minute dose of AI. As used herein, the terms“preventive treatment” and “prophylactic treatment” may be usedinterchangeably and may refer to a treatment performed in early stagesof phytoplankton contamination.

According to some embodiments, the composition may be applied byemptying containers containing the composition at one or more “droppingzones”. According to some embodiments, the composition may be applied atthe dropping zones without requiring mixing, stirring, spraying orotherwise spreading of the composition over the surface of the watersystem. According to some embodiments, the one or more dropping zonesmay be at the shore of the water body, thus advantageously obviating theneed for using boats or other delivery equipment as essentially shown inFIG. 8A and FIG. 8B herein.

According to some embodiments, the composition may be applied usinga“duster” similar to those used for spreading salt pesticides or grainsin agriculture. Dusting may be particularly useful when treating largewater systems. The formulation can be applied from a boat of any kindwithout any volume limitation at strategic “dropping” zones from wherethe compound can travel with the currents and aggregate along algalconcentrations.

Large quantities of the composition can be manufactured and packed insiloes of variable sizes (e.g. 10 s of tons). Optionally, the entiresilo can be shipped directly to the desired “dropping zone” where it canbe deployed. According to some embodiments, a spreader can be built intosuch a silo to better control the amount and rate of product used ineach “dropping zone”.

According to some embodiments, the preventive phytoplankton treatmentmay include applying at least two different photosynthetic microorganisminhibitors e.g. in an alternating order between treatments. As anon-limiting example, two consecutive treatments with H₂O₂-basedcompositions may be done followed by a third treatment with acopper-based composition.

According to some embodiments, a combination of two photosyntheticmicroorganism inhibitors may be applied in a single treatment, e.g.copper- and H₂O₂-based compositions may be applied simultaneously.

According to some embodiments, the combined or alternating action ofmore than one photosynthetic microorganism inhibitor may (a) preventaccumulation of resistant strains and (b) affect different types ofphytoplankton with various sensitivities and (c) reduce the total amountof photosynthetic microorganism inhibitor that is applied. Eachpossibility is a separate embodiment.

According to some embodiments, the inspection may be remote, such as bybuoys, air or space.

According to some embodiments, the preventive phytoplankton treatment(beginning of season) enables using about 2-fold, 3-fold, 5-fold,10-fold, 15-fold, 20-fold, 50-fold less AI, or any value there betweenper season as compared with late bloom treatment (also referred toherein as “responsive treatment” or “end of season treatment”). Eachpossibility is a separate embodiment.

According to some embodiments, if 0.33 kg of the active ingredient e.g.is Sodium percarbonate per 1,000 m² is applied, this is equivalent to0.325 gr/m² (Molecular weight of Sodium percarbonate−2Na₂CO₃*3H₂O₂=314gr, releases 3 molecules of H₂O₂ i.e. 102 gr of H₂O₂). Accordingly, 1 kgof sodium percarbonate releases 325 gr H₂O₂. This corresponds to 0.11gr/m² which is 11-fold less than the minimal amounts used in the variousstudies.

According to some embodiments, the preventive phytoplankton treatmentprevents development of a full-scale bloom altogether.

According to some embodiments, the preventive phytoplankton treatmentbrings about at least a 40% or at least a 60% reduction in phytoplanktonbiomass after 24 hours. According to some embodiments, the preventivephytoplankton treatment brings about at least an 80% or at least a 90%reduction in phytoplankton biomass after 48 hours.

According to some embodiments, the treatment will change the ratiobetween cyanobacteria to non-toxic algae by 1.5-fold, by 4-fold, by10-fold or more within 24-72 hours from initiation of the treatment(vis-à-vis the ratio before treatment). Each possibility is a separateembodiment. According to some embodiments, the ratio may be determinedby measuring photosynthetic pigments (that capture the light energynecessary for photosynthesis) as a proxy of specific phytoplanktonspecies such as: chlorophyll-a, chlorophyll-b, chlorophyll-c1,chlorophyll-c2, fucoxanthin, peridinin, phycocyanin, and/orphycoerythrin. Additionally or alternatively, the ratio may bedetermined spectroscopically by measuring the fluorescence emitted fromthe photosynthetic pigments or using phytoplankton cell count(microscopy, cell-sorting), or thermal imaging. Each possibility is aseparate embodiment. Without wishing to be bound by any theory, thetreatment methodology and slow-release composition, disclosed herein,changes the ecological balance in the water body so that cyanobacteriaget lysed to otherwise exterminated, followed by which non-toxic algae(which are minimally affected by the sub-lethal dose of the AI) takeadvantage and proliferate in high numbers. This ‘self-healing’ mechanismof the water body sustains the treatment and prolongs the results as thenon-toxic algae further compete with the cyanobacteria to keep their lownumbers at bay.

According to some embodiments, the preventive phytoplankton treatmenteliminates or at least significantly reduces the concentration of toxinproducing cyanobacteria or algae in the water system.

According to some embodiments, the preventive phytoplankton treatmentobviates the need to chlorinate the supplied drinking water.

According to some embodiments, the preventive phytoplankton treatmenteliminates bad smell and taste of the water in the water system, whichmay be particularly advantageous for recreational and aquaculturepurposes.

According to some embodiments, the preventive phytoplankton treatmentfurther decreases the population of small planktonic crustaceans (e.g.Daphnia sp. or Copepod sp. 0.2-5 millimeters in length) that feed on thephytoplankton (e.g. by at least 10%, at least 50% or at least 90% within1, 7 and 30 days respectively). These organisms that feed onphytoplankton blooms increase the incidence of pipe-clogging. Accordingto some embodiments, the reduced crustacean population lowers the needto apply highly poisonous pesticides (e.g. abamectin) that are typicallyemployed to inhibit, reduce or exterminate the growth of planktoniccrustaceans. Advantageously, the preventive phytoplankton treatment maythus reduce the wear and tear of filters and pumps.

According to some embodiments, the preventive phytoplankton treatmentfurther reduces or prevents occurrence of Enterobacteriaceae species.

Advantageously, due to the above benefits of the preventivephytoplankton treatment, the present invention reduces the overallseasonal operation costs by as much as 90%, thus making treatment oflarge water bodies (>10 km²) feasible technically, environmentally andfinancially.

According to some embodiments, the method further comprises, conductinga follow-up inspection in order to decide if additional treatment isnecessary. Each possibility is a separate embodiment. Certainembodiments of the present disclosure may include some, all, or none ofthe above advantages. One or more technical advantages may be readilyapparent to those skilled in the art from the figures, descriptions andclaims included herein. Moreover, while specific advantages have beenenumerated above, various embodiments may include all, some or none ofthe enumerated advantages.

According to some embodiments, there is provided a method for preventingand/or eliminating development of phytoplankton blooms in water bodieslarger than 5,000 m², the method comprising applying a buoyant algaecidecomposition to about 0.001-20% of the surface at a pre-defined locationenabling the wind to passively disperse the composition.

According to some embodiments, the method further comprises an initialstep of inspection for development of a phytoplankton bloom, wherein theinspection comprises determining phytoplankton biomass and/orconcentration. According to some embodiments, applying the compositioncomprises applying the composition preventively prior to formation of avisible/detectable phytoplankton bloom and/or scum. As used herein, theterm “visible” may refer to a bloom/scum floating at the surface of thewater body visible to the naked eye or to bloom detectable by laboratoryanalysis.

According to some embodiments, the method comprising applying a buoyantcomposition at a pre-defined “dropping zone” upwind of an infected areaof the water body, such that wind and current cause the composition todrift towards and/or together with the phytoplankton bloom; therebymitigating, inhibiting, preventing and/or eliminating the development ofphytoplankton bloom.

According to some embodiments, applying the composition comprisesapplying the composition when the biomass of the phytoplankton in the“dropping zone” is below 10 μg/L chlorophyll-a or about 20,000 cells/mLor less.

According to some embodiments, the composition is applied such that theconcentration of the algaecide in the water system/body is in the rangeof 10⁻⁷-10⁻¹² ppm, on average, depending on the depth, within 24 hoursof its application over essentially the entire volume of the water body(e.g. at least 85%, at least 90%, or at least 95% of the water body).According to some embodiments, the composition is applied such that thealgaecide in the water body is below 10⁻⁹ ppm, on average, over theentire volume of the water body within 72 hours, within 48 hours, orwithin 24 hours. According to some embodiments, the herein disclosedpreventive treatment may be conducted prior to an algal orcyanobacterial bloom and thus ensures that the amount of toxins measuredin the water system is lower than 0.1 μg/L (10% of the maximal allowablelevel by WHO).

According to some embodiments, applying the composition comprisesapplying the composition to about 0.001-25% of the surface of the waterbody. According to some embodiments, applying the composition comprisesapplying the composition to about 0.001-15% of the surface of the waterbody. According to some embodiments, applying the composition comprisesapplying the composition to about 0.001-10% of the surface of the waterbody.

According to some embodiments, the water body is a reservoir, an ocean,a lake, a dam, a pond, an estuary, a gulf, a sea, or a river. Accordingto some embodiments, the water body has a size of at least 10,000 m².According to some embodiments, the water system has a size of at least 1km², or 10 km², or 100 km².

According to some embodiments, the composition is formulated to staysubmerged within the photic zone of the water body. In some embodimentthe photic zone has a depth of about 0.1-1 m below the surface of thewater body, about 0.02-1.5 m below the surface of the water body, about0.1-2 m below the surface of the water body, or about 0.1-5 m below thesurface of the water body.

The term “photic zone” as used herein refers to the layer of water in awater body that is exposed to sunlight. According to some embodiments,the depth of a photic zone may be up to 1 meter, up to 10 meters or upto 100 m depth. The depth of the photic zone depends on the density ofthe phytoplankton population. For example, it may range between 0.1 mduring a massive algal bloom to 100 m when the phytoplankton populationis less than 10,000 cells/ml. The depth of a photic zone of a water bodymay further vary depending on the time of the day, season, geology orgeography of the water body.

According to some embodiments, the composition is configured to releasethe algaecide for at least 0.5 hour, at least 1 hour, at least 2 hoursor at least 6 hours, after application thereof. Each possibility is aseparate embodiment.

According to some embodiments, the composition is applied prior to analgal or cyanobacterial bloom, such that the amount of toxins measuredin the water body, including in vicinity to the area being applied,within 72 hours, within 48 hours, or within 24 hours from application islower than 1 μg/L.

According to some embodiments, the composition is formulated to staysubmerged at a depth of about 0.02-2 m below the surface of the waterbody.

According to some embodiments, the composition comprises 80-99.5% w/walgaecide 0.5-20% w/w coating material. According to some embodiment therate of Active Ingredient (AI) release from the buoyant algaecidecomposition can be adjusted by altering the relative proportions of theAI and coating material. The smaller the fraction of the coatingmaterial the faster the release of the AI.

According to some embodiment the duration of the phytoplankton treatmentwith the AI is determined by the rate of AI release from the buoyantalgaecide composition. The slower the release the longer the exposure ofthe phytoplankton to the AI.

According to some embodiment the longer the exposure of thephytoplankton to the active ingredient (AI) the larger is the fractionof phytoplankton cell death.

It is understood that the number of subsequent treatments, as well asthe frequency of the treatments (the time between subsequenttreatments), may be determined according to the release rate of the AI.

According to some embodiments, the composition is applied such that theaverage concentration of the algaecide in the water system declines to10⁻⁹-10⁻¹⁵ ppm within 24 hours, over essentially the entire volume ofthe water body (e.g. at least 85%, at least 90%, or at least 95%).

According to some embodiments, applying the composition comprisesapplying the composition to about 0.001-25% of the surface of the waterbody. According to some embodiments, applying the composition comprisesapplying the composition to about 0.001-15% of the surface of the waterbody. According to some embodiments, applying the composition comprisesapplying the composition to about 0.001-10% of the surface of the waterbody.

According to some embodiments, the slow release of the active materialwithin the photic zone exposes the toxic cyanobacteria to the AI for aduration that is sufficient to activate massive cell death.

Another advantage of the coated composition is that it is far lesscorrosive to the airplanes that deliver or distribute or spread it overthe treated water body.

Certain embodiments of the present disclosure may include some, all, ornone of the above advantages. One or more technical advantages may bereadily apparent to those skilled in the art from the figures,descriptions and claims included herein. Moreover, while specificadvantages have been enumerated above, various embodiments may includeall, some or none of the enumerated advantages.

In addition to the exemplary aspects and embodiments described above,further aspects and embodiments will become apparent by reference to thefigures and by study of the following detailed descriptions.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be described in relation to certain examples andembodiments with reference to the following illustrative figures so thatit may be more fully understood. The patent or application file containsat least one drawing executed in color. Copies of this patent or patentapplication publication with color drawing(s) will be provided by theOffice upon request and payment of the necessary fee.

FIG. 1A-FIG. 1C show time series photographs of 10 ml vials containing 5grams of coated granular copper sulfate with 0, 0.5, 1, 2.5 or 5% (w/w)of coating material. The raw copper salt (“0% coating”) sunk immediatelyafter dispersion. In contrast, the coated copper composition sunk to thebottom and resurfaced within a short time. (A) photograph of the watersurface 2 hours after dispersion of copper-based AI compositionscontaining (from left corner) 0%, 0.5%, 1%, 2.5% and 5% (w/w) of coatingmaterial; (B) a time series pictures of the vials from 5 min to 24hours, as marked; (C) exemplification from (B) of the remains of thegranules at bottom of the vials after 5 min, 30 min, 2 hours and 5hours.

FIG. 2 schematically illustrates an experimental set-up for testing thebuoyancy of the herein disclosed compositions, including (1) a balance;(2) a measuring pod with an aperture; (3) an underneath hook to measureweight; (4) a beaker filled with water simulating an aquatic system; (5)a weighing-pan.

FIG. 3A-FIG. 3H show representative time series photography of coatedNADCC (97% (w/w) AI and 3% (w/w) coating) floating or during floatation.Note the arrows showing specific samples.

FIG. 4 shows representative photographs of glasses filled with water andthe composition detailed in Table 1 with an increased coating percentage(50%, 15%, and 2.5% (w/w) left to right). The pictures were taken 30 minafter 25 grams of each composition were placed in the water.

FIG. 5A-FIG. 5B show representative photographs of sodium percarbonateplaced in 15 ml vials containing 5 grams of uncoated AI (left) and 5grams of coated-AI (right), at time 0 (FIG. 5A). After vigorous mixing(FIG. 5B) all coated formulation sank and immediately started toresurface.

FIG. 6 shows two 10-liter cylinders filled with water and supplementedwith sediment after one hour of treatment with the same dose of coppersulfate pentahydrate. The left cylinder was treated with the granules ofcopper sulfate pentahydrate (mimicking standard treatment), whichimmediately sank into the sediment. The right cylinder was treated witha buoyant copper-based formula, coated with 2.5% floating agent, thatfloated on the water and released its content into the water column(top-down).

FIG. 7 shows a comparison graph between three approaches conducted overone year, at 50-hectare ponds: (1) no treatment: solid black lineindicates a natural development of cyanobacterial bloom infestation; (2)Responsive, late stage treatment according to: solid gray line indicatessharp drops in bloom levels after every treatment with 50 kg/ha totaling1.75 tons over one year; (3) preventive treatment: dotted black line andarrows indicating eight sequential treatments of 5 kg/he totaling 200kg—a reduction of ˜90% in the total dose.

FIG. 8A and FIG. 8B show photographs of part of the shore where twopersons deposited the 500 kg product within a very short time. Thecompound was deposited in large piles of ˜5-10 kg each in the water(FIG. 8A). Soon enough, within 10-30 min, the granules started toresurface (i.e. designated by the arrows) and moved with the windtowards the algal scum (FIG. 8B). Total time for the piles to dispersedthemselves was 24-36 hours.

FIG. 9 depicts algaecide concentrations at various areas of anirrigation pond after being applied locally, opposite the target area.Upper figure “Day 1” details measurements that were taken 0-3 hoursafter treatment. Lower figure, “Day 2” details measurements that weretaken 24 hours after treatment. Note the dramatic change inchlorophyll-a concentrations within 24 hours, and the minimal AIconcentrations in the water within the first 24 hours of the treatment.

FIG. 10A-FIG. 10B show photographs of a 75,000 m² irrigation pond in theNegev that was infested with the Microcystis sp. and was treated with150 kg of copper-based floating formulation (FIG. 10A) before and (FIG.10B) after the treatment.

FIG. 11 depicts NOAA satellite imaging showing high levels ofcyanobacteria present in Chippewa Lake, Ohio, shortly before treatment(yellow and red pixels on August 3, top panel), that were completelycleared immediately after treatment (August 11 and onward, black pixels,lower panels). Grey pixels represent clouds.

FIG. 12A-FIG. 12B show Qualitative microscopic images of (FIG. 12A)Pre-treatment, most of the phytoplankton captured by the microscope wasof cyanobacterial species, mostly Planktothrix sp. and Anabaena sp.(FIG. 12B) three days post-treatment, no toxin-producing cyanobacteriawere captured. The phytoplankton captured by microscopic imaging wasmostly beneficial green algae, mainly Diatom sp. and Chlamydomonas-likesp. Few Spirulina sp., a nontoxic cyanobacterium, were also captured.

FIG. 13 shows relative measurements of Dissolved Oxygen (DO); the ratioof total eukaryotic algal biomass vs. cyanobacterial biomass—the‘Resistance Index’ (Algae vs. Cyano); Clogging potential meter; and pH.The measurements were taken daily, at 8 am, for 9 consecutive days andfrom different points in the lake. The measurements of DO, Algae vs.Cyano, and Clog Meter were normalized to day 0.

FIG. 14 is a picture of the Chippewa Lake, Ohio, showing protein foamformation throughout the lake, day 3 post-treatment.

FIG. 15 shows microcystin levels measured in Chippewa Lake since theMedina County Park District initiated weekly measurements of cyanotoxinsin 2016. The lake freezes between December and March. Red dotted arrowindicated the initiation of the treatment with the herein disclosedcomposition.

FIG. 16 depicts the outcome of a seasonal treatment with the hereindisclosed compositions in the irrigation reservoir of Kibbutz Nitzanim,indicating the dramatic impact of the treatment on algal levels, itsprolonged effect, as well as its ability to influence species-variety infavor of non-toxic ones (1 kg/ha.≈1 lb/acre).

FIG. 17 shows the amount of copper used as an algaecide in the KibbutzNitzanim irrigation reservoir during the years 2014-2018.

FIG. 18 shows visible changes in the water quality of the pond nearTaihu Lake, China treated with Sodium Percarbonate (Lake Guard™ Oxy).The upper panel shows the pond, pre-treatment. The lower panel shows thepond, 12 weeks post-treatment.

FIG. 19A-FIG. 19B show changes in chlorophyll (FIG. 19A); andphycocyanin (FIG. 19B) following treatment.

FIG. 20A-FIG. 20B shows changes in pH (FIG. 20A) and dissolved oxygen(FIG. 20B) following treatment.

DETAILED DESCRIPTION

In the following description, various aspects of the disclosure will bedescribed. For the purpose of explanation, specific configurations anddetails are set forth in order to provide a thorough understanding ofthe different aspects of the disclosure. However, it will also beapparent to one skilled in the art that the disclosure may be practicedwithout specific details being presented herein. Furthermore, well-knownfeatures may be omitted or simplified in order not to obscure thedisclosure.

Definitions

The term “phytoplankton” as used herein refers to Microorganismsperforming photosynthesis in aquatic environments. The two major groupsof phytoplankton are: (1) Cyanobacteria (also referred to as “Blue-greenAlgae”) and (2) Microalgae (i.e. eukaryotic photosyntheticmicroorganisms).

Non-limiting examples of cyanobacterial species include: Microcystissp., Nodularia sp., Cylindrospermopsis sp., Lyngbya sp., Planktothrixsp., Oscillatoria sp., Schizothrix sp., Anabaena sp., Pseudanabaena sp.,Aphanizomenon sp., Umezakia sp., Nostoc sp., Spirulina sp. Their knowncyanotoxins include: microcystins, nodularins, anatoxin,cylindrospermopsins, lyngbyatoxin, saxitoxin, and lipopolysaccharides.

Non-limiting examples of algae include: Karenia sp., Gymnodinium sp.,dinoflagellates, Prymnesium sp. (aka golden algae). Their list of toxinsincludes paralytic shellfish poisoning (PSP), neurotoxic shellfishpoisoning (NSP), aplysiatoxins, BMAA, brevetoxin, and ptychodiscus.

As used herein, the term “non-toxic algae” refers to algae which do notproduce toxins of a kind or at a concentration hazardous to theecosystem of the water system. According to some embodiments, non-toxicalgae do not produce paralytic shellfish poisoning (PSP), neurotoxicshellfish poisoning (NSP), aplysiatoxins, BMAA, brevetoxin, andptychodiscus.

As used herein, the term “non-toxic cyanobacteria” refers tocyanobacteria, which do not produce toxins of a kind or at aconcentration hazardous to the ecosystem of the water system. Accordingto some embodiments, non-toxic cyanobacteria do not producemicrocystins, nodularins, anatoxin, cylindrospermopsins, lyngbyatoxin,saxitoxin, and lipopolysaccharides.

As used herein, the term “Phytoplankton Blooms” refers to a populationexplosion of phytoplankton in waterbodies. The phenomenon is identifiedwhen large quantities of buoyant photosynthetic micro-organisms float atthe photic depth (where light intensity is higher than 1% that of thesurface water) or on the water surface. It refers to the phenomenon whencyanobacteria or microalgae species multiply their biomass in alogarithmic manner over a period of one day, a week, two-weeks, a month,a season.

The terms “algicides” or “algaecides” as used herein refers to compoundscapable of exterminating, lysing, killing, inhibiting growth of,inhibiting proliferation of, inhibiting photosynthesis or otherwisereducing/preventing/inhibiting/treating phytoplankton infestation.Non-limiting examples of suitable algaecides include oxidizers (e.g.hypochlorite, H₂O₂ or H₂O₂ producing chemicals such as sodiumpercarbonate), phosphate chelating agents (e.g. alum-salts, bentoniteclay), copper-based compounds, potassium permanganate and combinationsthereof. According to some embodiments, the algaecide may include acombination of algaecides, such as, but not limited to, H₂O₂ andcopper-based algaecides, which combination may have a synergisticeffect, thus enabling reducing the overall usage of chemicals. As usedherein, the term “lowest lethal dose” refers to the least amount of drugthat can produce death of the phytoplankton when exposed to thealgaecide for less than 24 h.

Without being bound by any theory, in addition to the effect of abioticparameters, sensitivity of cyanobacteria to H₂O₂ depends on the specificconditions in each water body, such as the phytoplankton composition andits ability to decompose H₂O₂ (Weenink et al., 2015, Combattingcyanobacteria with hydrogen peroxide: a laboratory study on theconsequences for phytoplankton community and diversity. Front Microbiol6: doi:10.3389/fmicb.2015.00714). Accordingly, in preparation for atreatment, the threshold concentration above which the active ingredient(e.g. H₂O₂) kills the phytoplankton/cyanobacteria when applied as asingle dose is determined.

According to some embodiments, the lethal dose may be determined asfollows:

-   -   1. Collect cells e.g. using a phytoplankton net.    -   2. Collect the cells (e.g. by rinsing the net with a small        volume of distilled water, such as 100 mL (the exact volume        depends on the cell density)).    -   3. Withdraw a sample to vials (e.g. 1 mL) and centrifuge vials.    -   4. Apply a range of H₂O₂ concentration using a stock solution        (e.g. 0, 0.5, 1, 2, 4 and 10 mg/L).    -   5. Vortex and wait 30-60 min.    -   6. Spin the vials and measure the absorbance at 620, 680 and 730        nm wavelengths. This enables assessment of the amount of        pigments released from dying cells.

The term “waterbody” as used herein refers to any type of reservoir,aquaculture, basin, salt or fresh or brine waters, ocean, gulf, sea,stagnant water or river.

The term “water system” as used herein may refer to include any body ofwater whether natural or manmade.

As used herein, the terms “Active ingredient (AI)”, “core material”,“raw material” and “technical compound” refer to any reactive compoundthat is designated to cause reactivity against microorganisms in thewater system. Non-limiting examples of AIs include detergents,antibiotics, anti-photosynthetic, algaecides. According to someembodiments, the AI may be any phytoplankton or zooplankton inhibitingagent.

In some embodiments, the term “mitigation” as used herein refers toreducing phytoplankton biomass by 90%, 80%, 70%, 60%, 50% or more within30 min, 90 min, 6 hours, 1 day, 2 days, or one week, from treatmentapplication. Each possibility is a separate embodiment.

As used herein, the terms “necrosis” and “necrotic cell death” may beused interchangeably and refer to a form of cell injury which results inthe premature death of cells due to, for instance, a high level ofpoison or toxins that impairs cell function/structure.

As used herein, the term “Program cell death (PCD)” refers to cell deathinduced by an internal or external signal(s) mediated by anintracellular genetically controlled program.

In some embodiments, the term “season” as used herein refers to theperiod of time extending between initiation of phytoplankton logarithmicgrowth (defined either by cell-density levels that increase by more than2-fold within a period of time: one day, a week, two-weeks, or a month);or when cell density exceeds 8 μg chlorophyll-a/L or 8,000 phytoplanktoncells/ml; and the end of logarithmic growth (when cell-density levelshardly change or even naturally drop below 10 μg chlorophyll a/L or20,000 phytoplankton cells/ml). It should be noted that in some cases,in some places, based on the foregoing criteria a “season” may not be anannually recurring phenomenon, rather one that takes place all yearround.

The term “periodic treatment” as used herein refers to a treatment every24 hours, 2 days, a week every 2-4 weeks, once a month, once a year, ortwice a year. Each possibility is a separate embodiment. According tosome embodiments, the periodic treatment may be seasonal treatment.

The term “infected area” as used herein refers to an area that iscontaminated with phytoplankton biomass in a cell density that is aboutor larger than 10 μg/L chlorophyll-a concentrations or above 20,000phytoplankton cells/ml. The area can be defined using probes orstandard-laboratory extraction methods to detect photosynthetic pigments(that capture the light energy necessary for photosynthesis) as a proxyof specific phytoplankton species such as: chlorophyll-a, chlorophyll-b,chlorophyll-c1, chlorophyll-c2, fucoxanthin, peridinin, phycocyanin,phycoerythrin. Detection can also be done spectroscopically, by thefluorescence emitted from the photosynthetic pigments or usingphytoplankton cell count (microscopy, cell-sorting), or thermal imaging.Determination and mapping of the infected area can be done using dronesor a satellite aerial inspection via multispectral imaging. It can alsobe done with a probe connected to a boat that crisscrosses the waterbody to effectively monitor the water surface.

The term “critical surface tension” as used herein refers to the surfacetension of solid bodies, powders etc. It can be measured as a surfacetension of liquids (or liquid mixtures) that leads to the completespreading of liquid on the solid surface. The critical surface tensionvalue is measured in dyn/cm. It can be defined by a matrix of liquidsmixed together to change the water surface tension strength asexemplified also by (Ghahremani et al., Der Chemica Sinica 2: 212-221,2011). Different materials have different surface tension values, forexample Parafines ˜23-24 dyn/cm, Teflon, ˜19-21 dyn/cm, Polyvinulchloride ˜45 dyn/cm etc.

As used herein, the terms “floating composition” and “buoyantcomposition may be interchangeably used and refer to compositionsformulated for floating on the surface and/or for staying submerged inthe water column without sinking to the bottom of the water system.According to some embodiments, the floating/buoyant composition may beessentially equally dispersed throughout the water column. According tosome embodiments, the floating composition may be formulated to reach acertain depth (above ground) of the water column (e.g. 0.01-5 cm belowthe surface, or 10-200 cm below the surface or 20-100 cm below thesurface).

As used herein, the term “acid value” refers to mass of KOH in mg thatis required to neutralize 1 g of a fatty acid, such as one gram of thecoating material.

As used herein, the term “consisting essentially of” with regards to theherein disclosed compositions refers to compositions including less than2% w/w, less than 1% w/w, less than 0.5% w/w, less than 0.1% w/w, lessthan 0.05% w/w or less than 0.01% w/w of ingredients other than thosedisclosed. Each possibility is a separate embodiment.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises” or “comprising”, whenused in this specification, specify the presence of stated features,steps, operations, but do not preclude or rule out the presence oraddition of one or more other features, steps, operations, or groupsthereof. According to some embodiments, the term “comprising” may bereplaced by the term “consisting essentially of” or “consisting of”.

The terms “about” and “approximately” refer to a reasonable variationfrom a stated amount that retains the ability to achieve one or morefunctional effect to substantially the same extent as the stated amount.The term may also refer herein to a value of plus or minus 10% of thestated value; or plus or minus 5%, or plus or minus 1%, or plus or minus0.5%, or plus or minus 0.1%, or any percentage in between.

Compositions

According to some aspects, the present disclosure is directed tocompositions for mitigating, treating, inhibiting, ameliorating, and/oreliminating phytoplankton growth in water bodies, the compositioncomprising:

-   -   i. an active ingredient at concentration of 80.0-99.5% (w/w).    -   ii. a coating material at concentration of 0.5-ive % (w/w).        wherein the critical surface tension of the composition is        between 15-60 dyn/cm and wherein the relative density of the        composition, prior to being submerged in water, is above 1.0        g/cm³.

According to some embodiments, the composition is formulated such thatthe relative density decreases to below 1.0 g/cm³ 0.1-60 minutes,0.25-60 minutes, 5-60 minutes, or 10-60 minutes after being submerged inwater. Each possibility is a separate embodiment.

According to some embodiments, the composition consists of the activeingredient and the coating material i.e. includes essentially only thelisted ingredients (active ingredient and coating) and less than 40%,less than 20%, less than 10%, less than 5%, 1% or 0.1% of otheringredients (impurities or inert materials). Each possibility is aseparate embodiment.

In some embodiments, the critical surface tension of the composition isbetween 20-45 dyn/cm, or more specifically 28-32 dyn/cm. Each optionrepresents a separate embodiment of the invention. According to someembodiments, the critical surface tension of the composition is about 30dyn/cm. According to some embodiments, the critical surface tension ofthe composition is about 35 dyn/cm.

In some embodiments, the concentration of the active ingredient is75-99.5%, more specifically 80-99%, or more specifically 95-99%, eachoption representing a separate embodiment of the invention. In someembodiments, the active ingredient is a photosynthetic microorganisminhibitor. In other embodiments, any active ingredient desired to beformulated in a buoyant composition may be formulated according to thepresent invention.

According to some embodiments, the active ingredient may include anyactive ingredient, including any type of water disinfectant, capable oftreating, inhibiting and/or eliminating, mitigating growth of aquaticpests such as phytoplankton blooms.

Non-limiting examples of suitable active ingredients includeoxygenic-releasing agents, chlorine releasing agents, bromine-releasingagents, iodine-releasing agents, peroxide-based compounds, copperreleasing agents, manganese-releasing agents, aluminum releasing agents,photosynthesis inhibitors, and any combination thereof.

Specifically, the active agent may be or include sodium percarbonate,copper sulfate pentahydrate, calcium hypochlorite, sodiumdichloroisocyanurate, alum salts, titanium dioxide,phthalimido-peroxy-hexanoic acid, quaternary ammonium compounds, sodiumhypochlorite, chlorine, bronopol, glutaral, alkyl*dimethyl benzylammonium chloride*(50% c14, 40% c12, 10% c16), alkyl*dimethyl benzylammonium chloride*(60% c14, 30% c16, 5% c18, 5% c12),1-(alkyl*amino)-3-aminopropane monoacetate*(47% c12, 18% c14, 10% c18,9% c10, 8% c16, 8% c8), trichloro-s-triazinetrione, sodiumdichloro-s-triazinetrione, sodium dichloroisocyanurate dehydrate, sodiumbromide,poly(oxyethylene(dimethyliminio)ethylene(dimethyliminio)ethylenedichloride), 2-(thiocyanomethylthio)benzothiazole, isopropanol, sodiumchlorate, sodium n-bromosulfamate, mixture with sodiumn-chlorosulfamate, 1,3-dibromo-5,5-dimethylhydantoin, dodecylguanidinehydrochloride, tetrakis(hydroxymethyl)phosphonium sulphate (thps),1-bromo-3-chloro-5,5-dimethylhydantoin, sodium chlorite, potassiumpermanganate, ammonium bromide, copper triethanolamine complex, chlorinedioxide, 2,2-dibromo-3-nitrilopropionamide, 5-chloro-2-methyl-3(2h)-isothiazolone, sodium dichloroisocyanurate dehydrate, silver, silversodium hydrogen zirconium phosphate (ag0.18na0.57 h0.25zr2(po4)3), aminoacids (such as but not limited to: arginine, glutamine, L-lysine,methionine), copper ethanolamine complex, methyldodecylbenzyl trimethylammonium chloride 80% and methyldodecylxylylene bis(trimethyl ammoniumchloride) 20%, lanthanum, aluminum sulfate, 2,4-Dichlorophenoxyaceticacid (2,4-D), 1,1′-Ethylene-2,2′-bipyridyldiylium dibromide (Diquatdibromide), 1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]pyridin-4-one(fluridone), N-(phosphonomethyl)glycine (glyphosate),5-(methoxymethyl)-2-(4-methyl-5-oxo-4-propan-2-yl-1H-imidazol-2-yl)pyridine-3-carboxylicacid (Imazamox),(RS)-2-(4-Methyl-5-oxo-4-propan-2-yl-1H-imidazol-2-yl)pyridine-3-carboxylicacid (Imazapyr), [(3,5,6-Trichloro-2-pyridinyl)oxy]acetic acid(Triclopyr), Endothall (3,6-endoxohexahydrophthalic acid as potassiumsalt or amine salt) or any combination thereof. Each possibility is aseparate embodiment.

In some embodiments, the concentration of the coating material may be inthe range of about 0.5-20% (w/w) of the composition, 0.5-15% (w/w) ofthe composition, 0.5-25% (w/w) of the composition, 1-20% (w/w) of thecomposition, 0.5-5% (w/w) of the composition or any other suitable rangewithin the range of 0.1-40% (w/w) of the composition. Each optionrepresents a separate embodiment of the invention.

According to some embodiments, the coating material may have a partitioncoefficient (log P) of above 1, above 1.5 or above 2. Each possibilityis a separate embodiment.

According to some embodiments, the concentration of the coating materialis less than 30% (w/w), less than 20%, less than 10% (w/w) of thecomposition, less than 5% (w/w) of the composition, less than 2% (w/w)of the composition or less than 1% (w/w) of the composition. Eachpossibility is a separate embodiment.

According to some embodiments, the coating material may include one ormore compounds selected from the group consisting of cellulosederivatives, ground plant biomass, saturated hydrocarbons, resinousmaterials, foam, natural or synthetic latex, waxes, paraffin, rosin,hydrophobic materials, superhydrophobic material, fatty acids and theirderivatives and silicone derivatives or any other suitable compound orcombination of compounds having the herein disclosed desired criticalsurface tension. Each possibility is a separate embodiment.

According to some embodiments, the coating material may be or include afatty acid. According to some embodiments, the fatty acid may be anaturally occurring fatty acid. According to some embodiments, the fattyacid may be an unbranched chain. According to some embodiments, thefatty acid may have an even number of carbon atoms, from 4 to 28.According to some embodiments, the fatty acid may be long-chain fattyacids (LCFA) with aliphatic tails of 13 to 21 carbons. According to someembodiments, the fatty acid may be saturated. According to someembodiments, the fatty acid may be unsaturated. According to someembodiments, the fatty acid may be a triglyceride.

According to some embodiments, the coating material may be or include awax. As used herein, the term wax refers to organic compounds that arelipophilic, malleable solids at ambient temperatures, typically having amelting point between 55-90° C. According to some embodiments, the waxmay be natural or synthetic. According to some embodiments, the wax maybe an animal wax, such as bee wax or a plant wax, such as camauba wax.According to some embodiments, the coating material may be or includeparaffin.

Non-limiting examples of suitable coating materials include: Decanoicacid, sodium salt; Octadecanoic acid, ammonium salt; Glycerides, animal,reaction products with sucrose; Glycerides, palm-oil, reaction productswith sucrose; Glycerides, tallow, reaction products with sucrose;Glycerides, vegetable-oil, reaction products with sucrose; Fatty acids,tall-oil, maleated, compds. with triethanolamine; Dodecanoic acid,potassium salt; Xanthylium,3-[(2,6-dimethylphenyl)amino]-6-[(2,6-dimethylsulfophenyl)amino]-9-(2-sulfophenyl)-,inner salt, sodium salt (1:1); Siloxanes and silicones,3-[(2-aminoethyl)amino]propyl Me, di-Me, methoxyterminated;Di-2-ethylhexyl azelate; Tetraethoxysilane, polymer withhexamethyldisiloxane; Poly(oxy-1,2-ethanediyl),alpha-phenyl-omega-hydroxy-, styrenated; 9-Octadecanoic acid2-(2-hydroxyethoxy)ethyl ester; Isoamyl butyrate; Benzenesulfonic acid,coctadecyl-, sodium salt; Fatty acids, C18-unsatd., dimers,hydrogenated, polymers with ethylenediamine, olyethylene-polypropyleneglycol 2-aminopropyl Me ether and polypropylene glycol diamine. Theminimum number average molecular weight is 51300; Sulfuric acid,monooctyl ester; Siloxanes and silicones, 3-aminopropyl Me, Me stearyl;Octadecanoic acid, ester with 1,2,3-propanetriol; 9-Octadecenoic acid(Z)—, 2,3-dihydroxypropyl ester; Octadecanoic acid, 2-hydroxyethylester; Isopropyl stearate; Behenic acid; Stearyl alcohol; Hexanedioicacid, polymer with N-(2-aminoethyl)-1,3-propanediamine, aziridine,(chloromethyl)oxirane, 1,2-ethanediamine, N,N″-1,2-ethanediylbis?1,3-propanediamineU, formic acid andalpha-hydro-omegahydroxypoly(oxy-1,2-ethanediyl); Siloxanes andsilicones, 3-hydroxypropyl Me, ethers with polyethylene glycol mono-Meether; Stearyl dimethyl benzyl ammonium chloride; Octadecanoic acid,2,3-dihydroxypropyl ester; Octadecanoic acid, butyl ester; Butylstearate; Fatty acids, canola-oil; Octanoic acid; Castor oil,hydrogenated, polymer with adipic acid, ethylenediamine and12-hydroxyoctadecanoic ac; Phenyl didecyl phosphite; Hexanedioic acid,polymer with 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, hydrazine,3-hydro; 9-Octadecanoic acid, monoester with oxybis(propanediol);Poly(oxy-1,2-ethanediyl),α-undecyl-ω-hydroxy-, branched and linear;Poly(oxy-1,2-ethanediyl), α-(4-nonylphenyl)-ω-hydroxy-, branched;Siloxanes and Silicones, di-Me, 3-hydroxypropyl Me, 3-hydroxypropylgroup-terminated, ethoxylated propoxylated; Octadecanoic acid, 2-2,bis(hydroxymethyl)-1,3-propanediyl ester; 9-Octadecenoic acid,12-hydroxy-, (9Z,12R)—, monoester with 1,2,3-propanetriol; Glyceryldistearate; Fatty acids, coco, reaction products with2-((2-aminoethyl)amino)ethanol, bis(2-carboxyethyl)deri; Sorbitanmonolaurate; Sorbitan monostearate; Decanoic acid, calcium salt; Fattyacids, tall oil, polymers with bisphenol A, epichlorohydrin,ethylenemanuf.-by-product di; Glyceryl tris(12-hydroxystearate);Siloxanes and silicones, di-Me, Bu group- and3-((2-methyl-1-oxo-2-propenyl)oxy)propyl group-te; Fatty acids,C18-unsatd., trimers, compounds with oleylamine; Sodium lauryl sulfate;Lauryl sulfate; Siloxanes and silicones, di-Me, polymers withsilica-1,1,1-trimethyl-N-(trimethylsilyl) silanamine hydrolysis productsand silicic acid trimethylsilyl ester; Octadecanoic acid, calcium salt;Fatty acids, C18-unsatd., trimers, reaction products withtriethylenetetramine; Siloxanes and silicones, 3-aminopropyl Me, di-Me,[[(3-aminopropyl) ethoxymethylsilyl]oxy]-terminated, 4-hydroxybenzoates;Siloxanes and silicons, hydroxy Me, Me octyl, Me(gamma-omega-perfluoroC8-14-alkyl)-oxy, ether; Trisiloxane,1,1,1,3,5,5,5-heptamethyl-3-octyl-; Cetyl stearyl octanoate;9-Hexadecenoic acid; Phenyl tris(trimethylsiloxy)silane; Octadecanoicacid, 2-ethylhexyl ester; Fatty acids, tall-oil, esters withpolyethylene glycol mono(hydrogen maleate), compounds with amides fromdiethylenetriamine and tall-oil fatty acids; Siloxanes and silicones,di-Me, hydroxy Me, ethers with polypropylene glycol mono-Bu ether;Dodecanoic acid, zinc salt; Polypropylene glycol stearyl ether; Silane,(3-chloropropyl)trimethoxy-; 9-Octadecenoic acid (9Z)—, diester with1,2,3-propanetriol; Lauryl methacrylate polymer; Butylacrylate-hydroxyethyl acrylate-methyl methacrylate copolymer; Butylacrylate, 2-hydroxyethyl methacrylate, methyl methacrylate and styrenecopolymer; Butyl methacrylate, 2-ethylhexyl acrylate and styrenecopolymer; Hexadecanoic acid, diester with 1,2,3-propanetriol;Hexadecanoic acid, monoester with 1,2,3-propanetriol; Sorbitantristearate; Dodecylphenol; Dodecylbenzenesulfonic acid,diisopropylamine salt; Dodecylbenzenesulfonic acid, triethylamine salt;Silane, triethoxyoctyl-; 2-Ethylhexyl 12-hydroxystearate; Hexadecanoicacid, 2-ethylhexyl ester; 2-Ethylhexyl monohydrogen phosphate; Magnesiumdodecyl sulfate; Octadecanoic acid, tridecyl ester; Octadecanoic acid,monoester with 1,2,3-propanetriol; Dodecanoic acid, octadecyl ester;Silane, trimethoxy(2,4,4-trimethylpentyl)-; C8-12 triglycerides;Trisiloxane, 1,3,3,5-tetramethyl-1,1,5,5-tetraphenyl-; Sodiumdodecylnaphthalene sulfonate; Tetradecanoic acid, magnesium salt;Heptadecanoic acid; Octadecanoic acid, magnesium salt; Octadecanoicacid, zinc salt; Hexadecanoic acid; Octadecanoic acid; Octadecanoicacid, 12-hydroxy-, homopolymer, octadecanoate; Fatty acids, coco; Fattyacids, vegetable-oil; Glycerides, tallow sesqui-, hydrogenated; Fattyacids, tall-oil; Fatty acids, tallow; Fatty acids, tallow, hydrogenated;Fatty acids, soya, ethoxylated; Fatty acids, coco, ethoxylated;Siloxanes and silicones, di-Me, Me Ph; Siloxanes and Silicones, di-Me,hydroxy-terminated, ethoxylated; Siloxanes and silicones, Me3,3,3-trifluoropropyl; Poly(methylhydrosiloxane); Polydimethylsiloxane,methyl end-blocked; Chlorinated wax; Petroleum wax; Paraffins(petroleum), normal C5-20; Fatty acids, tall-oil, polymers withglycerol, pentaerythritol, phthalic anhydride and rosin; Glycerides,mixed mono- and di-; Fatty acids; Fatty acids, C8-18 and C18-unsatd.;Fatty acids, C16-18 and C18-unsatd.; Fatty acids, C8-18 and C18-unsatd.,potassium salts; Fatty acids, C8-18 and C18-unsatd., sodium salts;Glycerides, C8-18 and C18-unsatd. mono- and di-; Glycerides, C14-18mono- and di-; Fatty acids, coco, polymers with glycerol and phthalicanhydride; Silanes and siloxanes, 3-cyanopropyl Me, di-Me,3-hydroxypropyl Me, ethers with polyethylene-polypropylene glycolmono-Me ether; Siloxanes and silicones, di-Me, 3-hydroxypropyl Me,ethers with polyethylenepolypropylene glycol mono-Me ether;Silicone-glycol copolymer; Siloxanes and silicones, di-Me,3-hydroxypropyl Me, ethers with polyethylenepolypropylene glyc; Dimethylsiloxane polymer with silica; Siloxanes and silicones, di-Me, Me vinyl;Siloxanes and silicones, di-Me, hydroxy-terminated, ethers withpolypropylene glycol mono-Bu eth; Siloxanes and silicones, ethoxy Me;Glycerides, palm-oil mono- and di-, hydrogenated, ethoxylated;Glycerides, C16-22; Siloxanes and silicones, di-Me, Me hydrogen,reaction products with polyethylene glycol monoacet; Siloxanes andsilicones, di-Me, Me hydrogen, reaction products withpolyethylene-polypropylene glycol monoacetate allyl ether; Siloxanes andSilicones, di-Me, di-Ph, Me Ph, polymers with Me Ph silsesquioxanes;Siloxanes and Silicones, di-Me, Me Ph, polymers with Me Phsilsesquioxanes; Siloxanes and Silicones, di-Ph, Me Ph, polymers with MePh silsesquioxanes; Fatty acids, coco, diesters with polyethyleneglycol; Glycerides, C14-18 mono- and di-, ethoxylated; Fatty acids,tall-oil, esters with ethylene glycol; Glycerides, coco mono- and di-,ethoxylated; Glycerides, soya mono-; Fatty acids, corn-oil; Fatty acids,cottonseed-oil; Fatty acids, soya; Fatty acids, tall-oil, polymers withethylene glycol, glycerol, isophthalic acid, pentaerythritol andpropylene glycol; Fatty acids, tallow, hydrogenated, dimers, diketenederivs.; Fatty acids, tallow, hydrogenated, ethoxylated propoxylated;Fatty acids, linseed-oil; Glycerides, C16-18 and C18-unsatd. mono- anddi-; Siloxanes and silicones, Me octyl; Silane, dichlorodimethyl-,reaction products with silica; Fatty acids, tall-oil, diesters withpolypropylene glycol; Fatty acids, tall-oil, sesquiesters with sorbitol,ethoxylated; Siloxanes and silicones, di-Me, 3-hydroxypropyl Me,ethoxylated; Siloxanes and silicones, di-Me, 3-hydroxypropyl Me,ethoxylated propoxylated; Siloxanes and silicones,di-Me,[(methylsilylidyne)tris(oxy)tris-, hydroxy terminated, ethers withpolyethylene-polypropylene glycol monobutyl ether; Fatty acids, coco,hydrogenated; Siloxanes and silicones, di-Me, 3-hydroxypropyl Me, etherswith polyethylene glycol mono-Me eth; Fatty acids, tall-oil, esters withethoxylated sorbitol; Fatty acids, tall-oil, polymers with glycerol,isophthalic acid and rosin; Siloxanes and Silicones, di-Me, Me hydrogen,reaction products with polypropylene glycol monoallyl ether; Glycerides,C14-22 mono-; Glycerides, C14-22 mono-, acetates; Siloxanes andsilicones, di-Me, 3-hydroxypropyl Me, Me2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl, ethers withpolyethylene-polypropylene glycol mono-Me ether; Glycerides, mixeddecanoyl and octanoyl; Siloxanes and Silicones, polyoxyalkylene-;Polyglyceryl oleate; Polyglyceryl stearate; or any combination thereof.Each possibility is a separate embodiment.

According to some embodiments, the coating material may be or includeBehenic acid; Octadecanoic acid, 2,3-dihydroxypropyl ester; Glyceryldistearate; Hexadecanoic acid; Octadecanoic acid; Fatty acids; Fattyacids, C8-18 and C18-unsatd.; Fatty acids, C16-18 and C18-unsatd.; Fattyacids, C8-18 and C18-unsatd., potassium salts; Fatty acids, C8-18 andC18-unsatd., sodium salts; Glycerides, C8-18 and C18-unsatd. mono- anddi-; Glycerides, C14-18 mono- and di-; Fatty acids, coco, polymers withglycerol and phthalic anhydride;

According to some embodiments, the coating material may include anycompound having one or several of the following attributes: (a) composedof inert compound/s by the inert ingredients approved for use inpesticide products as listed by the US EPA(https://www.epa.gov/pesticide-registration/inert-ingredients-overview-and-guidance);(b) does not chemically react with the AI; (c) low cost; (d)biodegradable; (e) enable the AI to interact with the water system andto release its content over time at water temperatures below 45° C.; (f)coating (w/w) percent of the total composition should be below 20%,preferably below 10% or more preferably below 5%; (g) no by-product ofthe coating or the combination of the coating with the AI causeenvironmental hazardous; (h) sustained shelf life (humidity, hightemperature during shipping), preferably over 1 year (depending on theAI); (i) coating melting temperature between 50-90° C.; coating is solidabove 20° C. Each possibility is a separate embodiment.

According to some embodiments, the granule size is such that an optimaltradeoff between buoyancy (the smaller the granule, the less it weighs,the more likelihood it remains on the water surface) and solubility (thesmaller the granule, the larger its surface area, hence the faster itdissolves). Thus, the granule size should be optimized to ensure fastresurfacing while on the one hand allowing release of the AI and on theother preventing it from diffusing into the water surface at earlystages of the resurfacing phase.

According to some embodiments, the composition has a form of granulessuch as, but not limited to, percarbonate granules.

According to some embodiments, the granule size is in the range of50-150 μm, 150-1500 μm, 200-1000 μm, 0.3-15 mm or 1-10 mm. In principle,the larger the granules are, the less coating required. Each possibilityis a separate embodiment.

According to some embodiments, the granule size of the AI may beadjusted such that the composition remains at a depth of 0.02-2 m,0.1-1.5 m, 0.2-1 m or 0.2-0.5 m or any other suitable range within therange of 0.01 and 2 m below the surface of the water system. Eachpossibility is a separate embodiment, thus making the compositionpartially buoyant or semi-buoyant. According to some embodiments, atleast 99%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50% of theapplied composition may remain semi buoyant for at least 20 minutes, atleast 30 minutes, at least 1 hour or at least 2 hours after having beenapplied and/or after having resurfaced. Each possibility is a separateembodiment. Advantageously, due to the semi-buoyancy of the composition,it is particularly suitable for preventive treatment of early stages ofalgal infestation during which the pelagic algae are typically foundbelow the surface of the water system, i.e. prior to formation of algalmats on the surface of the water body.

Methods of Applying the Composition

According to some embodiment, there is provided a method for treating,inhibiting, and/or eliminating phytoplankton growth in water bodies, themethod comprising:

-   -   i. performing inspection for presence of a phytoplankton (e.g.        according to specific phytoplankton pigments),    -   ii. defining an infected area by coordinates,    -   iii. applying a buoyant composition locally, off-wind, opposite        to the infected area, so that the wind pushes the floating        algaecide particles towards the bloom;        thereby treating, inhibiting, ameliorating and/or eliminating        the phytoplankton growth.

According to some embodiments, the treatment may be prophylactic, thusenabling treatment with minute doses of active ingredient. As usedherein, the term “prophylactic treatment” may refer to a treatmentperformed in early stages of phytoplankton bloom. According to someembodiments, early stages of phytoplankton bloom may refer to aphytoplankton concentration of 10 μg/l or below, 5 μg/l or below, or 1μg/l or below. Each possibility is a separate embodiment. According tosome embodiments, early stages of phytoplankton bloom may refer to aphytoplankton concentration 20,000 phytoplankton cells/ml or below,8,000 phytoplankton cells/ml or below, or 5,000 phytoplankton cells/mlor below. Each possibility is a separate embodiment.

According to some embodiments, the buoyant composition may be the hereindisclosed buoyant composition comprising an active ingredient (e.g.photosynthetic microorganism inhibitor) at concentration of 80.0-99.5%w/w and a coating material at concentration of 0.5-20% w/w; wherein thecritical surface tension of the composition is between 15-60 dyn/cm andwherein the relative density of the composition, prior to beingsubmerged in water, is above 1 g/cm³. However, other buoyantcompositions such as, but not limited to, compositions comprising atleast one floating agent and at least one active ingredient may also beused and are thus within the scope of this disclosure.

According to some embodiments, applying the buoyant compositioncomprises applying the composition such that a concentration of theactive ingredient is less than 999·10⁻⁹-10⁻¹⁵ ppm in the aquatic system.

According to some embodiments, applying the buoyant compositioncomprises applying the composition to 0.001-10% of the surface of anaquatic system off-wind, and opposite to the infected area.

According to some embodiments, the prophylactic phytoplankton treatmentmay include applying at least two photosynthetic microorganisminhibitors e.g. in an alternating order between treatments. As anon-limiting example, two subsequent treatments with H₂O₂-basedcompositions may be done followed by a third treatment with acopper-based composition.

According to some embodiments, a combination of two photosyntheticmicroorganism inhibitors may be applied in a single treatment, e.g.copper- and H₂O₂-based compositions may be applied simultaneously.

According to some embodiments, the combined or alternating action ofmore than one photosynthetic microorganism inhibitor may (a) preventaccumulation of resistant strains and (b) affect different types ofphytoplankton with various susceptibilities and (c) reduce the totalamount of photosynthetic microorganism inhibitor that is applied. Eachpossibility is a separate embodiment.

According to some embodiments, the buoyant composition moves togetherwith the bloom in the aquatic system.

According to some embodiments, the method comprises periodicallytreating the aquatic system with the buoyant composition at aconcentration of less than 999·10⁻⁹-10⁻¹⁵. According to someembodiments, the method comprises periodically treating the aquaticsystem with the buoyant composition at a concentration of less than thelowest lethal dose of the algaecide.

According to some embodiments, the prophylactic phytoplankton treatment(beginning of season) enables using about 2-fold, 3-fold, 5-fold,10-fold, 15-fold, 20-fold, 50-fold less active ingredient, or any valuetherebetween per season as compared to late bloom treatment (alsoreferred to herein as “responsive treatment” or “end of seasontreatment”). Each possibility is a separate embodiment.

According to some embodiments, the prophylactic phytoplankton treatmentprevents full-scale blooms altogether.

According to some embodiments, the prophylactic phytoplankton treatmentbrings about at least a 40% or at least a 50% reduction in phytoplanktonbiomass after 24 hours. According to some embodiments, the prophylacticphytoplankton treatment brings about at least an 80% or at least a 90%reduction in phytoplankton biomass after 48 hours.

According to some embodiments, the treatment will change the ratiobetween cyanobacteria to non-toxic algae by 2-fold, by 4-fold, by morethan 10-fold within 24-72 hours from initiation of the treatment(vis-à-vis the ratio before treatment). Each possibility is a separateembodiment. According to some embodiments, the ratio may be determinedby measuring photosynthetic pigments (that capture the light energynecessary for photosynthesis) as a proxy of specific phytoplanktonspecies such as: chlorophyll-a, chlorophyll-b, chlorophyll-c1,chlorophyll-c2, fucoxanthin, peridinin, phycocyanin, and/orphycoerythrin. Additionally or alternatively, the ratio may bedetermined spectroscopically, by measuring the fluorescence emitted fromthe photosynthetic pigments or using phytoplankton cell count(microscopy, cell-sorting), or thermal imaging. Each possibility is aseparate embodiment. Without wishing to be bound by any theory, thetreatment methodology and slow-release composition, disclosed hereinchanges the ecological balance in the water body so that cyanobacteriaget lysed to otherwise exterminated, followed by which non-toxic algae(which are minimally affected by the sub-lethal dose of the AI) takeadvantage and proliferate in high numbers. This ‘self-healing’ mechanismof the water body sustains the treatment and prolongs the results as therising fraction of non-toxic algae further compete with thecyanobacteria to keep their low numbers at bay.

According to some embodiments, the method further comprises applying anadditional dose of the same or different active ingredient if thephytoplankton biomass is higher than 10 μg/l.

According to some embodiments, the prophylactic phytoplankton treatmenteliminates or at least significantly reduces the concentration of toxinsin the water system.

According to some embodiments, the prophylactic phytoplankton treatmenteliminates or at least significantly reduces the need to chlorinatewater.

According to some embodiments, the prophylactic phytoplankton treatmenteliminates or at least significantly reduces bad smell and taste of thewater in the water system, which may be particularly advantageous forrecreational and aquaculture purposes.

Advantageously, as the algaecide optimally distributes itself verticallyas well as spatially, it reduces the overall exposure of livingorganisms in the water to the active compound and leaves them ampleareas upwind or in deeper waters to escape to.

According to some embodiments, the prophylactic phytoplankton treatmentfurther reduces the population of small planktonic crustaceans (e.g.Daphnia sp. or Copepod sp. 0.2-5 millimeters in length) that feed on thephytoplankton (e.g. by at least 10%, at least 50% or at least 90% within1, 7 and 30 days respectively). These organisms are a correlatedby-product of the phytoplankton bloom which increases the incidence ofpipe-clogging. According to some embodiments, the reduced crustaceanpopulation reduces, in turn, the need or at least the requiredconcentration of the highly poisonous pesticides (e.g. abamectin) thatare typically employed to inhibit, reduce or exterminate the growth ofplanktonic crustaceans. Advantageously, the prophylactic phytoplanktontreatment may thus reduce the wear and tear of filters and pumps.

According to some embodiments, the prophylactic phytoplankton treatmentfurther reduces or prevents occurrence of Enterobacteriaceae species.

Advantageously, due to the above advantages of the prophylacticphytoplankton treatment, the present invention reduces the overallseasonal operation costs by as much as 90%, thus making treatment oflarge water bodies (>10 km²) feasible technically, environmentally andfinancially.

According to some embodiments, the composition may be applied using a“duster” similar to those used for spreading salt pesticides or grainsin agriculture. Dusting may be particularly useful when treating largewater systems. The formulation can be applied from a boat of any kindwithout any volume limitation at strategic “dropping” coordinates fromwhere the compound can travel with the currents and aggregate alongalgal concentrations.

Large quantities of the composition can be also manufactured and packedin siloes in variable sizes (10 s of tons). Optionally, an entire silocan be shipped directly to the desired “dropping zone” where it can bedeployed. A spreader can be built into such a silo to better control theamount and rate of product used in each “dropping zone”.

According to some embodiments, the method includes the performance offollow up assessments of the previously treated-area within a certainperiod of time, such as within 24 hours, within 2 days or within a week,in order to monitor the treatment's results and respond if, when andwhere it is required with a supplemental dose. Each possibility is aseparate embodiment.

According to some embodiments, the method further comprises, conductinga follow-up inspection every 24 hours, every 2 days, every week, every2-4 weeks, once a month, once a year, or twice a year in order to decideif additional treatment is necessary. Each possibility is a separateembodiment.

According to some embodiments, the coating process may have one orseveral of the following attributes:

-   -   Simple and affordable, preferably no more than two-steps        involved.    -   Safe to manufacture.        Methods for Preparing the Composition        According to some embodiments there is provided a method of        preparing/manufacturing a buoyant composition comprising        percarbonate granules, the method comprising heating the AI        granules to 45-60° C. during continuous stirring under nitrogen        environment in a sealed mixer; heating of hydrophobic coating        containing methyl esters of fatty acids (CAS NO 67762-38-3) or        methyl esters of higher fatty acids (CAS No. 67254-79-9) to        60-90° C., encapsulating the AI granules by the hydrophobic        coating during continuous stirring.        According to some embodiments, the method further comprises        cooling the composition to below 40° C. to obtain        sodium-percarbonate granules with a solid coating.

The following examples are presented in order to more fully illustratesome embodiments of the invention. They should, in no way be construed,however, as limiting the broad scope of the invention. One skilled inthe art can readily devise many variations and modifications of theprinciples disclosed herein without departing from the scope of theinvention.

EXAMPLES Example 1—Determination of the Optimal Coating

To determine the optimal percentage of coating required to provide (1)resurfacing of the composition and (2) slow-release of the compound, thefollowing protocol was established.

A given quantity (in weight) of AI was mixed with the coating material(see Table 1). Although it could be expected that more coating wouldresult in better buoyancy, in practice, the opposite happened. Withincertain parameters, the less coating material applied, the betterbuoyancy was achieved. Concurrently, less coating translated into ahigher rate of AI release from the composition.

TABLE 1 compositions of copper and a mixture of fatty acids withincreasing percentage of the coating (granule size distribution wasbetween 0.3-1.67 mm). CuSO₄•5H₂O, mixture of fatty (% weight) acids (%weight) Notes 99.5 0.5 FIG. 1A-FIG. 1C 99.0 1.0 97.5 2.5 95.0 5.0 90.010.0 85.0 15.0 80.0 20.0 75.0 25.0 Slurry. big agglomerates upon 70.030.0 crystallization. Neither release 60.0 40.0 of copper norresurfacing - even 50.0 50.0 after 3 days under ambient conditions (seeFIG. 2).

Surprisingly, as can be seen from Table 1 above, when the fraction ofcoating material was 25% or higher was applied to the AI, the final(dry) product lost buoyancy. When submerged under water it failed toresurface. When placed on the water surface it sunk to the bottom.Furthermore, the large amount of the coating inhibited the interactionwith the surrounding water and thus prevented solubilization and releaseof the active material.

In contrast, when the proportion of the coating used was lower (0.5-20%depending on the nature of the material used) the composition was ableto resurface despite its specific gravity being higher than 1.0 g/ml.Further, the floating composition agglomerate were able to release itsAI content to the surrounding water. More information is provided in theexamples below.

The resurfacing phenomenon can be seen in FIG. 1A-FIG. 1C, which showrepresentative time series photographs showing the buoyancy of granularcopper coated with 0, 0.5, 1, 2.5 or 5% (w/w) of coating material.

As expected, non-coated active ingredient (0.0% (w/w)) sank immediatelyto the bottom and quickly dissolved in the water, due to its hygroscopicnature.

Initial application of formulations with 0.5%-5.0% (w/w) resulted in thegranules mostly sinking to the bottom (FIG. 1A). However, as can be seenfrom FIG. 1B and FIG. 1C, within ˜30 min, all the granules, whichinitially submerged, resurfaced and advantageously remained buoyant.

Example 2—Preparation of Sodium Dichloroisocyanurate Buoyant Formulationwith a High Concentration of Photosynthetic Microorganism Inhibitor

In order to test the buoyancy of the herein disclosed compositions, anexperimental set-up, schematically illustrated in FIG. 2, was applied.In this set-up, a laboratory balance 1 (0-2,000±0.1 g) was positioned tomeasure the weight of a composition placed on a weighing-pan 5 immersedin a beaker filled with water 4. If the composition is non-buoyant (AIwithout the coating material) an increase in weight is anticipated(‘negative control’). Oppositely, if the composition is buoyant, theweight is expected to remain essentially unchanged.

The first composition tested was sodium dichloroisocyanurate (NADCC) 97%(w/w) encapsulated with wax (3%, w/w). The composition was prepared bymelting 3 g of wax in a 500 ml beaker. When completely dissolved, theNADCC was placed inside the beaker and mixed vigorously for 20 min in astandard laboratory chemical fume until the temperature of thecomposition returned to room temperature (22° C.). The surface tensionof the composition was measured to be 30 dyn/cm.

As expected, when 9.5 grams of un-encapsulated NADCC was placed on theweighing-pan a ˜5.3 g weight increase was observed. However, when 9.6grams of the coated sample was weighed, the initial weight increase wasonly 1.5-5% of the original weight—evidently due to semi-buoyancy of theformulation over the weighing-pan. The critical surface tension of thecomposition was measured and defined at 30 dyn/cm.

FIG. 3A-FIG. 3H represents time-series photography of coated NADCC (97%w/w, AI and 3%, w/w, coating material) of the experiment. Upon applyingthe composition on the water surface, the composition initially floated(FIG. 3A). However, shortly after application, agglomerates started toform, and a meniscus of the water surface was observed (FIG. 3B outlinedin the picture by the black dashes). When the water-tension was brokenby vigorous mixing of the water, the composition sank to the bottomwithin 30 seconds (FIG. 3C-FIG. 3H, follow the arrows). Unexpectedly,within 30 min, the NADCC agglomerates resurfaced. By the end of thetrial (within 60 min, not shown in FIG. 3), all aggregates resurfaced.

The rate of chlorine released from the AI: when 1.0 gram of encapsulatedproduct (97.5% AI and 2.5% covering material) were placed in a beakerwith 1.0 liter containing distilled water, under ambient room conditions(22° C.), and mixed vigorously it took almost 24 hours to release theentire chlorine to the medium as measured with YSI 9300 photometer. Incontrast, when the same test was done using water containing a highorganic content, in the form of 10⁷ Planktothrix sp. cells per ml, allAI content was released within 2 hours. These data indicated that therate of AI release from the encapsulated composition is stronglyaffected by the organic mass content in the water column in addition tophysical parameters such as the physical stirring motion in the water.

Example 3—Industrial Preparation of Copper Sulfate Buoyant Formulationwith High Concentrations of Photosynthetic Microorganism Inhibitor

A final weight of granular copper sulfate pentahydrate of 97.5 kg, witha granule distribution of 0.5-5.0 mm, was preheated to 50° C. in aribbon mixer designed for powder blending. An amount of 2.5 kgpre-melted mixture of methyl esters of higher fatty acids (CAS No.67254-79-9), at 70° C., was applied onto the blended mixture. Themixture was then blended for 20 min and the content's temperature thencooled to 22° C. (room temperature). For quality analysis, three samplesof 100 grams each were withdrawn from different locations in the batch.The buoyancy of the samples was measured utilizing the experimentalsetup described in FIG. 2. Advantageously, the samples of the abovedescribed coated composition caused a 31%±4% weight increase only. Incomparison, non-encapsulated copper showed a 50%±3% weigh increase. Thecritical surface tension of the composition was measured and defined at35 dyn/cm.

FIG. 4 shows representative photographs of glasses filled with water andthe compositions (as detailed in Table 1) with a decreasing coatingpercentage (50%, 15%, and 2.5% w/w, left to right). The compositionscontaining 15% and 2.5% (w/w) coating resurfaced within 30 min, whereasthe compositions having 50% (w/w) coating remained on the surface, incrystallized agglomerates that never resurfaced. Further, contrary tothe compositions with 2.5% and 15% coat-compositions that released theirAI content in less than 24 hours (the exact time required was stronglyaffected by the organic matter content, as shown also above), thecomposition with 50% coating failed to release its AI content over morethan 3 days. This was in contrast to the increasing amounts of AIreleased from the 15% and 2.5% coated compositions, as was apparent fromthe increasingly blueish color of the water column. The water containingthe 50% coat-composition remained colorless for at least three daysafter the time of application.

Example 4—Industrial Preparation of Sodium-Percarbonate BuoyantFormulation with High Photosynthetic Microorganism InhibitorConcentrations

This example details the coating of 98% (w/w) sodium percarbonate (SPC)with 2% (w/w) methyl esters of higher fatty acids (CAS No. 67254-79-9)coating. Since SPC is an oxygenic compound that tends to explode,careful measures were taken. For that, a sealed explosion proof mixeragitator coated with a Teflon layer, and equipped with a vacuum pump fordrying purposes, was used. Working temperature was kept at all timesunder 22° C. In order to melt the coat under ambient conditions, organicsolvents (e.g. ethanol, methanol, isopropanol) were used in 1:1proportion with the coating. The mixture of 1.0 kg coat and 1.0 kgmethanol were mixed for 1 hour with 49 kg of sodium percarbonate.Thereafter, the vacuum pump was turned on and sucked all volatileresidues from the chamber whilst the mixture was still agitated in themixer. After two hours, when the compound was completely dry, it wasopened and packed in 10 kg plastic boxes. The surface tension of thecomposition was measured was 35 dyn/cm.

FIG. 5A-5B shows 15 ml vials each containing 5 grams of uncoated AI(left) or 5 grams of a coated-AI sample (right)), at time 0 (FIG. 5A)and after vigorous mixing (FIG. 5B). The uncoated AI sank immediately.In contrast, the coated formulation formed a meniscus at the watersurface, partially sank, but resurfaced shortly thereafter. The smallerthe coated granules the faster they surfaced.

Example 5—Sedimentation Analysis

Two 10-liter cylinders were filled with water and supplemented withsediment. To one cylinder, granules of copper sulfate pentahydrate(mimicking standard treatment) were added, while a buoyant copper-basedcomposition was added to the other cylinder. As seen from FIG. 6 leftimage, the copper sulfate pentahydrate granules immediately sank intothe sediment. In contrast, when a buoyant copper-based composition (FIG.6—right image) was added, the composition remained suspended and itscontent released its content into the water column (top-down).

Example 6—Large Granules Resurface Faster

Two different formulations of granular CuSO4-5H2O were purchased fromIQV (https://iqvagro.com/en/). Two granular sizes were tested a)1.0-10.0 mm and b) 0.280-2.0 mm. The granules were coated with 5% w/w,10% w/w/ or 20% w/w coating composed of 67.5% fatty acids and 32.5%methyl esters of fatty acids, as essentially described in Example 3.

150 grams of each composition was tested on the bank of a 150,000 m²fresh-water pond, in northern Israel on Jul. 4, 2019. All sixformulations were similarly placed on a concrete floor approximately 30cm below the surface of the pond. All six samples were distributedwithin 2 min. The maximal time of resurfacing of the compositions wasdetermined visually and was recorded using digital photography. Theresults are summarized in Table 2.

TABLE 2 Resurfacing time of compositions Granules size 0.280-2.0 mm1.0-10.0 mm % coating 5% 10% 20% 5% 10% 20% (w/w) of the final productResurfacing  1 min  5 min 30 min  5 min  7 min 30 min start time Maxtime 40 min 60 min Within 30 min 45 min Within to resurface 36 hrs 12hrs for the whole pileAs was observed in Example 1, granules with lower percentage by weightof coating resurfaced faster than those with thicker coatings.Furthermore, larger granules (granule size of 1-10 mm), unexpectedly,resurfaced at a significant higher pace than smaller granules (granulesize of 0.280-2.0 mm).

Example 7—Comparison of Methods for Anti-Algal Treatment Methods inWater Reservoirs

A trial designed to test the herein disclosed preventive approach in themanagement of phytoplankton populations was conducted in three ˜50 hawastewater reservoirs, ˜15 m deep (280,000 m³), in Israel (see FIG. 7).The ponds were naturally inhabited by a mixed phytoplankton population,which was mainly dominated by Microcystis sp. during the bloom season.The reservoirs were tested regularly over a year during morning timeusing 3-6 biological samples and the data was averaged per each samplingday. Samples were analyzed using a YSI Exo-3 probe which couldsimultaneously measure: water temperature, pH, specific conductivity,dissolved oxygen, chlorophyll (in general, or chlorophyll-bspecifically) as well as phycocyanin (PC) concentrations.

One pond was reserved as a control and was not treated for the entireyear. Two other ponds were treated when cyanobacterial cell-density wasvisual to a naked eye—usually at 40-80 μg/l chlorophyll-a. Treatment wasthen applied at a rate of 5 g/m² (250 kg/pond or a theoreticalconcentration of 0.89 ppm). The third pond was treated whenphytoplankton biomass increased by 5-fold from its winter baseline. Doseregime was calculated at 0.5 g/m² (25 kg/pond or a calculatedconcentration of 0.089 ppm). All treatments were made with a buoyantcopper sulfate pentahydrate composition (95% w/w AI, 5% w/w coating).

Results: For the natural, undisturbed pond, a cyanobacterial bloom haddeveloped over the year (FIG. 7, black curve): while during wintertime,algal cell-count was low, towards the spring when temperatures rose, thephytoplankton cell-density increased steadily. Later, as weather becamehotter and days longer, the population doubled itself every few hoursthroughout the summertime and a sharp rise in algal cell-numbers wasthus evident. This phase came to a halt towards autumn time, and reacheda plateau mainly when resources became scarcer, and conditions lessfavorable. During wintertime, untreated algal cells were dormant only toreappear as conditions improved and repopulation commencing at a higherstarting point was observed.

When the pond was treated only according to visual inspection indicatingdevelopment of cyanobacterial scum, (FIG. 7, gray curve), at thebeginning of May, the treatment required a high dose of algaecide to beefficient. Altogether, 1.75 tons were applied, 875% more than thatrequired using the herein disclosed preventive approach (FIG. 7, dotted,black line)—where only 200 kg were used altogether. In addition, usingthe herein disclosed preventive approach, the total copper concentrationmeasured at the depth of 2 and 5 meters, 2 and 24 hours after treatment,were advantageously found to be below detection level (<0.00 mg/1).

Moreover, it was found that non-preventive treatment resulted in highnumbers of crustaceans (such as Daphnia sp.) requiring 159 liters ofaggressive pesticide control, whereas 90 liters of anti-crustaceancompound was required using the herein disclosed preventive approach.Thus, confirming the safety and cost effectiveness from an operationalaspect (as anti-crustacean compounds are toxic and sometime evencarcinogenic to humans and wildlife).

Example 8—Evaluating the Efficacy of Anti-Cyanobacterial TreatmentMethod in a Large Water Body

A pilot was conducted at a reservoir of ˜1,000,000 m² (1.5×10⁷ m³, southIsrael). The reservoir was infested with an early-moderate toxiccyanobacterial bloom (Anabaena sp. mixed with Aphanizomenon sp.).According to the water parameters (and considering the infestationlevel, geological characterizations, local flora combined with thereservoirs' history) it was decided to use a total quantity of 0.5 g/m²buoyant copper-based composition. Within 24 hours of decision, 500 kg ofthe formula (95% w/w AI, 5% w/w coating) in 25 kg bags were transferreddirectly to the water edge—from where two untrained personnel carriedand emptied the bags, one by one, onto the water (FIGS. 8A and 8B). Thetotal time of application was <15 min. In some cases, the compound wasdeposited in the water in large piles (as can be seen in FIG. 8A).

Once in the water, the hydrophobic particles immediately started tofloat and were carried by the South-Eastern wind towards thecyanobacterial aggregates (FIG. 8B). All compound including the one inthe piles resurfaced to the water surface within 24 hours (as some ofthe piles were bigger than the others). That was done in order toprovide a constant release of the active compound onto the water surfaceand (i) to reduce the cyanobacterial population within 24 hours; and(ii) to achieve a very low (<<0.001 ppb) algicidal residualconcentration in the water within 24 hours after the application.Indeed, while the concentration of total copper ions applied was 0.033ppm, in practice, chemical analysis of water samples withdrawn at 50 cmand 800 cm depth from the middle of the pond, 24 hours after applyingthe composition on the surface could not detect copper ions. Withoutbeing bound by any theory, the disappearance of the copper ions wasprobably due to them interacting with the abundant organic andnon-organic material in the water turning the free ions into inertmaterial (seehttps://www.who.int/water_sanitation_health/dwq/chemicals/copper.pdf).

Example 9—Evaluating the Low Concentrations and Minimal Coverage of theAnti-Algal Treatment Method in a Large Irrigation Pond

A seasonal treatment of algal bloom at an irrigation pond of ˜1.04 km²with a volume of 2.25×10⁶ m³ (25 m depth) was conducted fromFebruary-October 2017 in the northern Negev area, Israel. As detailed inFIG. 9, biomass and total copper concentrations were measured during thefirst two days to assess efficacy and minimal required AIconcentrations. Cyanobacterial biomass was measured using a YSI Exo-3probe that was supplied with a GPS. The probe was installed on aremotely operated boat that was sampling the whole water body at 30 cmdepth and was transmitting the data to a shore laptop. Water samples fortotal copper concentrations, as well as estimation of particle timetravel on the water, as well as final coverage, was done with a kayakand by using a laser distance/range measurer. Total copperconcentrations were measured with a YSI 9300 photometer in accordancewith manufacturer instructions. For the treatment of the area, 500 kgwere applied to the water surface in 10 kg bags (whole treatment lasted25 min).

After treatment was applied, the copper particles moved along the winddirection and current towards the other end of the pond (as summarizedin FIG. 9) where they concentrated at ˜10% off the infested area in thevicinity of the cyanobacterial aggregates. In general, algal biomass wasreduced by >95% within 24 hours with no harmful effect on local fauna,birds or fish. After the first treatment (end of February 2017) acontinuous treatment of 125 kg copper-sulfate buoyant composition wasapplied every 2-3 weeks when algal concentration exceeded 10 μg/lchlorophyll-a. Under this treatment regime, the algal cell-density didnot exceed 10 μg/l chlorophyll-a concentrations even when last measuredin the end of October 2017, and the overall amount of copper sulfateused in the floating composition was 1,050 kg (95% w/w copper sulfategranules, 5% w/w coating).

In contrast, in 2016, 7 aerial applications of 2000 kg granular,non-coated. copper sulfate was applied (total of 14 tons); however, theaverage cyanobacterial concentration remained high (60-80 μg/Lchlorophyll-a). Similarly, during 2015, 6 aerial applications ofnon-coated granular copper sulfate were applied, altogether a total of8,000 kg; however, the average chlorophyll-a concentration was 100-200μg chlorophyll-a/L),

Thus, it was concluded that treatment with the herein disclosed buoyantcomposition enabled maintaining low chlorophyll-a levels, much lowerthan those measured in 2015-2016 while lowering the amount of copperapplied by at least 80%, and thus dramatically reducing overall cost andecological impact of copper ions.

When summing up the data from day 1 and day 2 (FIG. 9), the theoreticalconcentrations of copper was calculated to be below 2.2×10⁻¹⁰ ppm, onaverage, over the entire volume of the water body (2.25×10⁹ liter), forday 1 and below 4.4×10⁻¹¹ ppm on average, over the entire volume of thewater body for day 2.

The superiority of the herein disclosed method and composition isparticularly surprising in view of other studies of phytoplanktontreatment which claim that abundance of Microcystis decreases only whenH₂O₂ is applied at doses of 4 mg/L and above, and that a highMicrocystis cell density rapidly reappears after completion of thetreatment (11 days when a H₂O₂ dose of 2 mg/L was applied) (Lin, L. Z.,et al. (2018) The ecological risks of hydrogen peroxide as a cyanocide:its effect on the community structure of bacterioplankton. J OceanolLimnol 36: 2231-2242).

Example 10—Treatment of a Microcystis sp. Infested Water Body

An irrigation pond infested with a heavy bloom of Microcystis sp. of 98pig/L chlorophyll-a concentrations in the Southern Negev, Israel, wasused in November 2017. The surface area of the pond was 75,000 m² andtotal volume of the reservoir was 1,125,000 m³. A 150 kg of hereindisclosed buoyant composition (95% w/w copper sulfate granules, 5% w/wcoating) was applied, the total copper level was 2.0 g/m². Four hourspost treatment the total copper concentration at 7 m depth wasadvantageously found to be below the detection levels of the YSI 9300photometer (<0.00 ppm). Two and a half hours post treatment the copperconcentrations at the surface where the buoyant composition was appliedwas 3 ppm, but below detection levels at 7 m depth. Total cyanobacterialbiomass reduction after two days was 97% (see FIG. 10). Dead cells wereobserved floating on the water surface where they were consumed byheterotrophic bacteria. The total theoretical copper concentrationsafter 2-3 h of treatment was calculated to be 1.3×10⁻⁹ ppm on average,over the entire volume of the water body.

Examples 11—Lake Treatments

Chippewa Lake (OH, USA): 1.3 km², has been suffering from algal bloomsin the past years, preventing recreation in the lake through most of theseason. A report prepared for Medina County in May 2019 listed severaltreatment alternatives ranging in cost from $0.5 million to $1.8million, none of which were feasible or economical. From an operationalpoint of view, and in terms of sheer size, the lake had fallen under thecategory of an ‘untreatable lake’.

With the goal of highlighting the simple scalability of the hereindisclosed method and compositions (95% w/w copper sulfate, 5% w/wcoating), cleaning the lake was initiated. The treatment was appliedonce a surge in cyanobacterial biomass was detected in the lake,reaching an alarming level of 280,000 cells/ml (14 times the standard),corresponding with an increase in cyanotoxin levels from 0.18 ppm to0.25 ppm over a one-week period. The surge in cyanobacterial levels wasvisible to the naked eye, with cyanobacterial mats spotted on theeastern shore of the lake, corresponding with NOAA satellite imagingtaken on August 3 (FIG. 11)—indicating high levels of cyanobacteria thatcovers over 50% of the surface of the lake.

Sampling Method: Using YSI ProDSS probe dissolved oxygen (DO), pH,chlorophyll-b (Chl-b is a proxy to determine the total biomass of greenalgae), phycocyanin (PC, is a proxy to determine the total biomass ofcyanobacteria) were measured. Clogging Potential Meter: a quantifier ofthe amount of the total solids in the water, measured in the time ittakes the water to clog a filter under constant pressure. Microscopy: aqualitative sampling of the microorganisms in the aquatic environment.Total phytoplankton was concentrated on a 33 μm filter, using a samplevolume of 3-4 gallon. Secchi Disk: Measures water clarity/turbidity.Satellite imaging for the presence of TCOs (provided by the NationalOceanic and Atmospheric Administration, NOAA). ELISA test formicrocystin, a cyanotoxin. This test measures the microcystin levels inthe water. Samples were taken weekly from two fixed points on theeastern side of the lake (provided by the Medina County Park District).YSI 9300 photometer: measures total copper ion concentration (Cu+2),hydrogen peroxide (H₂O₂) concentration, and alkalinity.

Starting on Aug. 5, 2019, all measurements, except for satellite imagingand ELISA tests, were taken daily, for 9 days, at 8 am every morning,from four different sampling points around the lake. Cyanotoxin levels(ELISA laboratory testing), and total coverage of cyanobacterial mats onthe water surface (satellite imaging), were assessed independently bythe local authorities.

A first assessment application of ˜0.9 lb/acre was applied on day 3,August 7th, in order to determine wind and current directions anddispersal patterns on the surface of the water. An operationalapplication followed on August 8th at a rate of 4.5 lb/acre. Resultswere analyzed and normalized against day 3.

Application Method:

The herein disclosed composition (here 95% w/w copper sulfate granules,5% w/w coating) was applied directly from a boat during the morninghours at a total dose rate of ˜5 lb/acre. The product, packaged in50-lbs bags, was gravity released from the edge of a moving boat. Oncethe waterborne product was organized over the western perimeter of thelake, it was carried by winds and currents that scattered the floatingparticles alongside cyanobacterial aggregates. The total applicationtime of 1,500 lb composition was less than 30 minutes. Within a fewhours, no algicidal particle were visible to the naked eye. Boatingactivities were not interrupted throughout the time of application.Measurements taken two-hours post-treatment indicated negligible levelsof copper ions (average of 0.3 ppm) in the immediate hourspost-treatment, dropping to below detection levels in the following day.

Results and Discussion:

Post-treatment phytoplankton assessments indicated a clear and immediateshift from dominating toxic cyanobacterial species (primarily Anabaenasp. and Planktothrix sp.) towards a healthy variety of eukaryoticnon-toxic green algae including Diatoms and different Chlamydomonas-likespecies (FIG. 12). Interestingly, the non-toxic cyanobacterium Spirulinasp. was also observed after the treatment. This strain is used as a“super-food” and is not considered toxic.

Changes in chlorophyll-b (Chl-b) and phycocyanin (PC) levels stronglycorrelated with the qualitative results obtained by microscopic imaging.The lake's ‘Resistance Index’ to cyanobacteria, which can be assessed bythe ratio between Chlorophyll-b and PC (total eukaryotic green algalbiomass vs. cyanobacterial biomass) increased significantly by 250%(FIG. 13), indicating a clear shift in the balance of power betweenthese two natural competitors—in favor of non-toxic species.

The amplified cycle ensued by the treatment, namely the collapse ofcyanobacterial populations after the treatment, followed by theprolonged oxidative stress due to the production of hydrogen peroxide,which again results in programmed cell death of naïve cyanobacterialpopulations, was observed in Chippewa Lake days after the treatment.Tens of acres of water surface were covered with a grayish-beige colorof protein-based-foam (FIG. 14). This phenomenon is attributed tocyanobacterial cell-lysis and is a clear indication that cyanobacterialcell-death continued progressing for days after treatment, long aftercopper levels were undetectable in the water (as detailed hereinafter).

Microcystin levels remained very low post-treatment (FIG. 15),indicating that the timing of the treatment, at the early stages of thebloom-surge, was effective. The sharp decline in cyanobacterial biomassdid not result in an increase in cyanotoxin-levels, confirming that thecyanobacterial cells were at their lag-phase stage, whencyanotoxin-accumulation in the cells is minimal (Wood et al., 2010). Hadthe treatment been applied a week or two later, during the exponentialgrowth phase of toxin-producing cyanobacteria, the levels of thecyanotoxins would have been much higher.

The pH levels, post-treatment, dropped from pH 8.5 to pH 7.95 (August9-11), a result of the reduction in overall photosynthetic activity (asa proxy to the relative decline in phytoplankton total biomass). Within4 days (August 12), pH levels rose to pH of 8.35 indicating there-initiation of photosynthetic activity by new, predominantly non-toxicphytoplankton variety (FIG. 12 and FIG. 13).

An additional confirmation about the advantages of early treatment, andits impact on the aquatic environment, came from the unchanged dissolvedoxygen levels before, during and after treatment (FIG. 13)—averting therisk of fish kill due to oxygen depletion (a typical outcome upon thecollapse of a massive bloom). In fact, no evidence for any adverseimpact to either the fauna or the flora of the lake was observed.

The clogging potential meter, which indicates the total solids in thewater, improved significantly by 400% immediately after treatment (FIG.13). This measurement serves as an additional indication to the changein populations in favor of non-toxic species: cyanobacteria are known torelease significant quantities of polysaccharides into the water (Harelet al., 2012), which increase water viscosity, and is associated withthe ‘swimmer's itch’ nuisance. Controlling polysaccharide concentrationsin the water, due to the collapse of cyanobacterial communities,breaches yet another ‘wall’ in the cyanobacterial defense mechanismagainst its natural competition, further enhancing the ‘ResistanceIndex’ against cyanobacteria. Breaking said network of polysaccharideproduction contributed to the water's increased filterability, asindicated by the clogging meter results. Copper ions (Cu+2)concentration in the water, sampled at 15-30 cm (6-12 inches) belowwater surface after 1-2 hours of the application, averaged around 0.3ppm. The copper ion concentration in days 1-3 post-treatment was <0.00ppm. Water alkalinity levels remained unchanged before and aftertreatment, at the range of 80 ppm (mg/L).

Combined, the results above indicate that the herein disclosedcomposition and method of use was selective against toxic cyanobacteriaand rehabilitated the ecological ecosystem in the lake in favor ofbeneficial species, which subsequently act as a biological buffer thatprevents cyanobacteria from reestablishing dominance in the aquaticsystem. Surprisingly, the effect of the treatment was still preservedwhen last measured in January 2020, thus confirming the ‘self-healing’of the lake by re-establishing of a desired and sustainable ecologicalbalance.

Israel, Nitzanim Reservoir (Seasonal Treatment):

Nitzanim Reservoir retains water for irrigation purposes. Prevention ofblooms in the reservoir is key to its continuous operation. It isrequired to supply its clients with water that meets both bacterialstandards as well as filterability standards at all times.

Israeli water associations operate some 600 reservoirs (10-190 acres insize) all over the country, designed to retain and manage recycledwastewater for irrigation.

Cyanobacterial outbreaks occur regularly in these reservoirs, likely dueto multiple reasons including a high level of nutrients (e.g.,phosphates and nitrates), high temperatures and sunlight intensity.Noticeably, water alkalinity is very high, ranging between 500-800 mg/lCaCO₃.

Over the years, Israeli irrigation ponds have been continuously treatedwith raw copper at a dose rate of 10-20 kg/acre (20-40 lb/acre); appliedeither from crop-dusters or manually, from a boat. The effectiveness ofthe treatment was rather poor, thus demanding frequent treatment. Inmany cases, the superintendents are forced to open and clean up pumpsand filters, sometimes on a daily basis to maintain water flow.Eventually, as water levels decrease towards the end of the irrigationseason, most reservoirs are forced to arrest the water flow due tocondensed algal blooms that clog and damage the pumps.

Materials and Methods:

The reservoir has a surface area of 15 acres and is about 50 ft deep(˜2.6 million cubic ft). It was monitored 2-3 times every week betweenJanuary and June of 2018.

Measurements:

-   -   Chlorophyll-a (as an indicator for total phytoplankton) was        measured by a handheld device (FluoroSense™, by Turner Designs,        USA).    -   pH    -   Temperature    -   Total particulate matter was assessed using a Clogging Potential        Meter (Israel Water Works Association, Israel) with a 33 μm        sieve filter. This device measures the time it takes for the        sieve to clog under constant water pressure. In principle, the        longer it takes for the filter to clog—the better is the water        quality.

Water was sampled from the intake flow in a fixed location in the middleof the reservoir, 6 feet above the bottom of the reservoir, and 45 feetbelow the surface when the reservoir is full.

Sampling was conducted in triplicates. All results were averaged foreach sampling point. Algal population analysis was conducted by amicroscope observation using hemocytometer cell count chamber.

Treatment Protocol

The treatments were conducted in accordance with the status of the algalbiomass as well as the water's filterability status. The parameterspresented were measured in the field and the company's laboratory.

Results and Conclusions:

A mix of toxic cyanobacterial species (Anabaena sp. and Microcystis sp.)constituted over 95% of the entire phytoplankton populations in thereservoir prior to treatment.

An initial treatment with the herein disclosed compositions (a firsttreatment a composition of 98% w/w sodium percarbonate and 2% coatingmaterial followed by treatments with a 95% w/w coated copper sulfatecomposition as indicated in FIG. 16) caused the total collapse of thetoxic bloom, keeping it for months to-come below dangerous levels (FIG.16). Analysis of the phytoplankton population clearly indicated that thetreatment outcome underscored “Killing the Winner” paradigm, whereby thedominant species were severely affected by the treatment, allowingnon-harmful eukaryotic algal species, mostly Monorapridium sp. andPediastrum sp. (far less sensitive to the treatment), to occupy the“vacant” ecological niche (FIG. 16).

Advantageously, the overall amount of copper applied in 2018, using theherein disclosed composition, was ⅓ of that used in the year before(FIG. 17) despite the intensification of toxic blooms in a nearby waterbody. Considering the ˜200% yearly rise in cyanobacteria populations invarious water bodies in Israel between 2014-2017, the actual reductionin copper applied in 2018, using Lake Guard™, is closer to ˜85%.

Since its launch in Israel in mid-2018, the herein disclosed composition(containing 98% (w/w) sodium percarbonate) has, in record speed,acquired ˜90% market-share.

China, Taihu Lake (near Yixing):

The pilot was conducted in an old fishpond (7,100 m², ˜2 acres), in thevicinity of Lake Tai, across a similarly contaminated ‘corridor’ linkinga waterway between the city of Yixing and Lake Tai. Ongoing efforts todeal with loads of cyanobacteria streaming through this ‘corridor’, bothfrom the lake as well as from the city at an average annual cost of $25million, have been fruitless.

The fishpond, which was contaminated with a very high cyanobacterialbiomass, was treated with a large dose to achieve an immediate declineof biomass levels.

Since launching in June 2019—multiple applications in different setupstook place in China. A recent example from a pilot designed inpreparation for a cleanup project of the waterways of Yixing (FIG. 18),on the shores of Lake Tai, one of the most known and worst cases oflarge-scale toxic blooms (˜2,250 km²).

Description of Application:

The fishpond was dosed with herein disclosed composition (98% w/w sodiumpercarbonate and 2% coating material) on August 7 and on Aug. 8, 2019.

The particles of the composition were applied so as to travel with thecurrents and the wind across the pond, interacting with thephytoplankton inhabiting the pond. Two consecutive treatments wereapplied. Each application lasted less than 5 min. By the afternoon ofAugust 8th, ˜6 h after the second application, all water parameters haveindicated a complete collapse of the bloom. One example (FIG. 19) is theinitial decline in chlorophyll and steeper decline of phycocyaninrepresenting changing levels of phytoplankton and cyanobacteria,respectively.

Two weeks later, the phytoplankton population, composed of eukaryoticgreen algae, showed a tremendous recovery with beneficial-speciesreplacing and likely outcompeting toxic cyanobacteria, and maintaining ahealthy aquatic ecosystem (FIG. 19).

Sampling Methodology:

Throughout the pilot period, quantitative measurements were made by YSIProDSS probe that measured dissolved oxygen, pH, chlorophyll, andphycocyanin (PC). Chlorophyll (Chl) measurements serve as a proxy fortotal algal biomass in the water. Phycocyanin (PC) levels serve as adirect proxy to total cyanobacterial biomass.

In parallel, qualitative assessments were made visually.

Results:

A. Changes in cyanobacterial and total algal levels:

Prior to treatment (at time 0), the PC and Chlorophyll values were 21.84μg/l and 22.32 g/l, respectively. After 48 hours, the PC dropped to 1.72μg/l (−93% from time 0) and Chlorophyll concentration was 9.39 μg/l(−58% from time 0) (FIG. 19A and FIG. 19B).

Two weeks later, on August 20th, the PC values continued to be stagnantat 2.04 μg/l, whereas Chlorophyll concentration increased to 45.34 μg/l(i.e. a 482% increase from its post-treatment lowest point). Since PClevels were not significantly altered in the span of two weeks, thesignificant rise in Chlorophyll levels reflects the rise in beneficialalgal populations over cyanobacterial species.

B. Changes in pH and dissolved oxygen (DO) values:

The dramatic reduction in photosynthetic and respiratory activities(consuming and releasing CO₂, respectively) had an immediate and directinfluence on the pH (FIG. 20A), which dropped from 9.05 to 8.29 within48 h. By August 20, two weeks later, pH levels dropped to 7.43.

The dissolved Oxygen (DO) levels decreased immediately post-treatmentdue to bacteria-mediated biodegradation process of dead cyanobacterialbiomass that depletes dissolved oxygen, and due to the collapse ofoxygen-producing cyanobacteria. The DO levels, however, increasedgradually, from its lowest point on day 2, as the oxygen-producing algaestarted to thrive in the rebalanced aquatic ecosystem—as indicated inthe increase in Chlorophyll, but not PC levels (FIG. 20B).

Visual inspection of the pond before treatment (upper panels) and aftertreatment (lower panels) confirmed the efficiency of the treatment (FIG.18).

Russia, a recreational lake in Park Pobedi, (The Republic of Tatarstan):

The treatment and follow up were conducted between October 2 and Oct.10, 2018.

The size of the lake was 40,000 m² surface area (10 acres).

Application:

Treatment with herein disclosed composition (98% w/w sodium percarbonate8 lbs/acre, was performed manually on the morning of Oct. 2, 2018, fromthe banks of the lake by an untrained local. The application took lessthan 10 minutes. Once waterborne, the floating, time-releasing particleswere pushed by the wind and currents and organized themselves along withcyanobacterial aggregations.

Sampling Methodology:

The lake was inspected, on a regular basis, for the past year by thelocal superintendent.

Results: No adverse impact was observed to the fauna or the flora in oraround the pond, and based on reports from the lake's superintendent(September 2019), no bloom episodes have been detected in the lake sincethe single treatment with the herein disclosed composition in October of2018, a year earlier. This is in sharp contrast to previous years, whereharmful algal blooms plagued the lake yearly.

While certain embodiments of the invention have been illustrated anddescribed, it should be clarified that the invention is not bound by thespecific embodiments described herein. Numerous modifications, changes,variations, substitutions and equivalents will be apparent to thoseskilled in the art without departing from the spirit and scope of thepresent invention as described by the claims, which follow.

The invention claimed is:
 1. A composition for mitigating, inhibiting,and/or eliminating phytoplankton growth in a waterbody, the compositioncomprising granules comprising an algicide at a concentration of80.0-99.5% (w/w) of the composition, wherein the algicide comprises anagent selected from the group consisting of hydrogen peroxide, sodiumpercarbonate and calcium hypochlorite; and a hydrophobic water insolublecoating material at a concentration of 0.5-20% (w/w) of the composition,wherein the coating material is selected from a saturated or unsaturatedfatty acid, a triglyceride or any combination thereof; wherein thecritical surface tension of the composition is between 15-60 dyn/cm, themelting temperature of the composition is 50-90° C. and an acid value ofthe composition is 3-8 mg KOH per gram and wherein the relative densityof the composition, prior to being submerged in water, is above 1.0g/cm³ such that the composition initially sinks after being applied, andwherein the composition becomes floating 0.25-60 minutes after beingsubmerged in water, thereby causing a surfacing of the composition tomitigate, inhibit and/or eliminate phytoplankton growth in thewaterbody.
 2. The composition according to claim 1, being formulatedsuch that the algicide is released into the water at water temperaturesbelow 45° C. within 24 hours of being applied.
 3. The compositionaccording to claim 1, being formulated as granules with a granule sizein the range of 100-1500 μm.
 4. The composition according to claim 1,being formulated as granules with a granule size in the range of 1-10mm.
 5. The composition according to claim 1, wherein the granules have aviscosity of 6-8 cP at 70° C.
 6. The composition according to claim 1,wherein the composition comprises granules with different concentrationsof coating material.
 7. The composition of claim 6, wherein the granulescomprise granules having 0.5-2.5% w/w coating material mixed togetherwith granules having 3-10% coating material, leading to slow/extendedrelease of the algicide, and/or an extended period of exposure of thecyanobacteria to the algicide.
 8. The composition according to claim 1,wherein the composition is configured to stay submerged at a depth ofabout 0.02-1 m below the surface of the water system after having beenapplied and/or after having resurfaced.
 9. The composition according toclaim 1, wherein the coating material has a partition coefficient (logP) of 1.5 or above.
 10. The composition according to claim 1, whereinthe composition has a critical surface tension of between 20-45 dyn/cm.11. The composition according to claim 10, wherein the composition has acritical surface tension of between 28-35 dyn/cm.